KENDRIYA VIDYALAYA SANGATHAN, KOLKATA REGION. Class XII SUBJECT: Biology (044) Theory

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KENDRIYA VIDYALAYA SANGATHAN, KOLKATA REGION

QUESTION PAPER FOR PRE BOARD EXAMINATION 2020-21

Class XII

SUBJECT: Biology (044) Theory

Time:3Hours Maximum Marks: 70 General Instructions:

(i)

All questions are compulsory.

(ii)

The question paper has four sections: Section A, Section B, Section C and Section D. There are 33 questions in the question paper.

(iii)

Section–A has 14 questions of 1 mark each and 02 case-based questions. Section–B has 9 questions of 2 marks each. Section–C has 5 questions of 3 marks each and Section–D has 3 questions of 5 marks each.

(iv)

There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.

(v)

Wherever necessary, neat and properly labeled diagrams should be drawn.

SECTION A

Q. No Questions Marks

1. What stimulates pituitary to release the hormone responsible for parturition? Name the hormone.

1

2. A structural gene has two DNA strands X and Y shown below. Identify the template strand giving reason.

1

3. In case of polyembryony, an embryo A develops from the synergids and the embryo B develops from the nucellus. State the ploidy of embryo A and B.

1

4. State the significance of colostrum in mother’s milk to a new-born infant. 1 5. Khorana and his colleagues synthesized an RNA molecule with repeating

sequence of AG nitrogenous bases (AGAGAGAGAGAG). It produced a tetrapeptide with alternating sequence of valine and tyrosine. Write down the codon for valine and codon for tyrosine.

OR

Mention two functions of the codon AUG.

1

6. Large holes are found in Swiss cheese. How are these formed? Name the bacteria involved.

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OR

In which ways have microbes played a major role in controlling diseases caused by harmful bacteria?

7. Expand the abbreviated form into their full forms: i) MALT

ii) CMI.

1

8. State the principle on which ELISA Works. 1

9. Why is it essential to have a selectable marker in a cloning vector? 1 10. A Couple quarreled with the hospital authority on suspicion that their child

had been exchanged after birth. The couple based their argument on the fact that their child is O blood group whereas they are A and B blood groups respectively. The doctor smiled and explained. How can the child be O blood group as explained by the doctor?

1

11. Assertion: Central dogma is the flow of information from DNA to

mRNA and then decoding the information present in mRNA in the form of protein.

Reason: In retroviruses, reverse of central dogma occurs.

a.

Both assertion and reason are true, and reason is the correct explanation of assertion.

b.

Both assertion and reason are true, but reason is not the correct explanation of assertion.

c.

Assertion is true but reason is false.

d.

Both assertion and reason are false.

1

12. Assertion: Metastatic cancers are more serious

Reason: These spread from one organ to other body organs and

there is increased interference with metabolic functioning.

a.

Both assertion and reason are true, and the reason is the correct explanation of the assertion.

b.

Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

c.

d.

Both assertion and reason are false

OR

Assertion: Ascaris is a Protozoa which causes ascariasis. Reason: It is a parasite of stomach.

a.

b.

c.

d.

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13. Assertion: Species diversity contributes to the well-being of an ecosystem. Reason: Rich biodiversity contributes to higher productivity of an

ecosystem

a.

b.

c.

d.

OR

Assertion: Conserving the biological diversity of the ecological hotspots is

very important component of efforts to safeguard the world’s biological heritage.

Reason: The hotspots of biodiversity cover a large percentage of the land

of earth

a.

b.

c.

d.

1

14. Assertion: Curdling is required in the manufacture of cheese. Reason: Lactic acid bacteria are used for the purpose.

a.

b.

c.

d.

1

15. Read the following and answer the questions (any four) given below:

BIODIVERSITY

There are three levels of biodiversity: genetic, species and Ecosystem diversity. Genetic diversity refers to totality of all inherited genetic variations within a population. All genes of a population are called gene pool.

Species diversity is of three types: Alpha diversity, beta diversity and gamma diversity.

Alpha diversity: It is the relative richness of different species in a habitat, the percentage of each and every species within a community.

Beta diversity: It is the relative richness of different species along a gradient from one Habitat to another Habitat within community. Birds of pond and birds of Agricultural area of same grassland.

Gamma diversity: It refers to the richness of different species in a range of habitats within a geographical area example Ocean, lakes, Ponds,

mountains, forests.

Ecological diversity is the variation in Species richness in different ecosystems of a geographical area.

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i) The variation in the constitution of genes of one species is called a) Genetic diversity

b) Species diversity c) ecological diversity d) biodiversity

ii) Which diversity is determined by various species of a given area? a) Genetic diversity

b) species diversity c) ecological diversity d) All the above

iii) What is the sum total of all genes in a population called a) gene frequency

b) gene Complex c) gene pool d) gene mutation

iv) How many types of species diversity is found? a) 2

b) 3 c) 4 d) 5

v) Diversity which refers to different species in a range of habitats within a geographical area is called

a) Alpha diversity b) Beta diversity c) Gamma diversity d) Delta diversity

16. Read the following and answer the questions (any four) given below:

Sewage treatment and microbes in production of biogas:

Municipal or city waste water method for cleaning of urban sewage is known as sewage treatment. Such water is treated with the help of heterotrophic bacteria which passes through the clearing process. Such plants are known as sewage treatment plants. It occurs in two phases.

1) Primary treatment process: Physical particles present in a sewage are removes through filtration and sedimentation. Which forms primary sludge.

2) Secondary treatment process: It is an aerobic process. These bacteria associated with filaments of molds present in the water and form flocs. Microbes, including bacteria consume organic matter present in effluent, hence most amount of organic matter present in a water is utilized due to chemical reaction and the BOD of the effluent decreases.

Biogas is the mixture of gases, which is used as fuel. Due to their anaerobic respiration like metabolic activities, such mixture of gases is produced in biogas plants. Biogas is also known as gobar gas.

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i) Which are the processes used to remove floating debris and grit? a) Filtration and leaching

b) Filtration and sedimentation c) Sedimentation and Distillation d) Filtration and Distillation

ii) Choose the correct option for effluent

a) bottom water of sludge produced in primary treatment of STPs. b) Upper free water of sludge produced by Filtration and

Sedimentation

c) Remnant water of STP.

d) Remnant water of activated sludge in STPs. iii) Which is the biological process of STPs?

a) Distillation b) Filtration c) Secondary d) Sedimentation

iv) Where does the flocs-formation and flocs sedimentation occur? a) In aeration tank, In effluent settling tank.

b) In anaerobic sludge digestor, Primary tank c) Primary tank, Secondary tank

d) Anaerobic sludge digestor, settling tank

v) Which is correct sequence for purification in STPs?

a) Effluent - Primary sludge – Flocs - Activated sludge - Biogas b) Flocs - Activated sludge - Effluent – Biogas

c) Primary sludge – Flocs - Activated sludge - Effluent- Biogas d) Primary sludge – Effluent – Flocs - Activated sludge – Biogas

SECTION – B

17. The procedure of GIFT involves the transfer of female gamete to the fallopian tube. Can gametes be transferred to the uterus to achieve the same result? Explain.

2

18. What is the significance of progesterone-estrogen combination as a contraceptive measure?

2

19. _{Name the cross made between the F1 generation hybrid and a double} recessive parent. How is it useful?

2

20. What would happen if histones were to be mutated and made rich in acidic amino acids such as aspartic acid and glutamic acid in place of basic amino acids such as lysine and arginine?

OR

Describe the structure of a nucleosome.

2

21. _{A plant with yellow flowers was crossed with a plant with red flowers. The F1} progeny obtained had orange flowers. Explain its inheritance pattern.

2 22. _{What is PCR? What are the steps involved in it?}

OR

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What is gene therapy? Name the first clinical case in which it was used. 23 Mention the site in the body where the B-cells and T-cells are formed. Give

one difference between them.

2 24 Label the three different tiers in the given age pyramid.

Mention the kind of population growth described by the pyramid.

2

25 _{The Tropical regions are likely to have more biological diversity than the} Temperate ones. Give two reasons to justify the statement.

2

SECTION – C

26. Draw and label the enlarged view of microsporangium of an Angiosperm. State the function of its innermost wall layer.

OR

With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.

3

27. The base sequence in one of the strands of DNA is TAGCATGAT. (i) Give the base sequence of the complementary strand.

(ii) How are these base pairs held together in a DNA molecule?

(iii) Explain the base complementarity rule. Name the scientist who framed this rule

3

28. Name the type of interaction seen in each of the following examples (i) Ascaris worm living in the intestine of human.

(ii) Wasp pollinating fig’s inflorescence.

(iii) Clown fish living among the tentacles of sea anemone. (iv) Mycorrhizae living on the roots of higher plants.

(v) Orchid growing on a branch of mango tree.

(vi) Disappearance of smaller barnacles when Balanus dominated in the coast of Scotland

3

29.

i) Identify A, B and C in the schematic diagram of an antibody given above

(ii) Write the chemical nature of an antibody and name the cells that produce antibodies in humans.

(iii) Mention the type of immune response provided by an antibody.

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30 A farmer noticed that nematode infection in tobacco plants has resulted in the reduction in the yield. Suggest a strategy which provides cellular defense for providing resistance to this pest. Explain the technique.

3

SECTION - D

31 The graph given below shows the variation in the levels of ovarian hormones during various phases of menstrual cycle:

a) Identify ‘A’ and ‘B’.

b) Specify the source of the hormone marked in the diagram. c) Reason out why A peaks before B.

d) Compare the role of A and B.

e) Under which condition will the level of B continue to remain high on the 28th_day?

OR

Given below is the diagram of a human ovum surrounded by a few sperms. Observe the diagram and answer the following questions:

a) Compare the fate of sperms shown in the diagram. b) What is the role of zona pellucida in this process?

c) Analyze the changes occurring in the ovum during the process. d) How is the entry of sperm into the ovum facilitated?

e) Specify the region of female reproductive system where the event represented in the diagram takes place.

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32. i) Define aneuploidy.

ii) How is it different from polyploidy?

iii) Describe the individuals having the following chromosomal abnormalities. a. Trisomy of 21st_chromosome

b. XXY c. XO

OR

In a plant tallness is dominant over dwarfness and red flower is dominant over white. Starting with the parents work out a dihybrid cross. What is standard dihybrid ratio? Do you think the values would deviate if the two genes in question are interacting with each other?

5

33 a) A recombinant DNA is formed when sticky ends of vector DNA and foreign DNA join. Explain how the sticky ends are formed and get joined?

b) Observe the diagram given below and answer the questions that follow:

i. Name the organism in which the vector shown is inserted to get the copies of the desired gene.

ii. Mention the area labelled in the vector responsible for controlling the copy number of the inserted gene.

iii. Name and explain the role of a selectable marker in the vector shown

OR

i. Name the source from which insulin was extracted earlier. Why this insulin no more in use by diabetic people?

ii. Explain the process of synthesis of insulin by EH Lilly company.

iii. How is the insulin produced by human body different from the insulin produced by the above-mentioned company?

5

PREPARED BY:

DOLI CHAUDHURI, PGT BIOLOGY KV NO 1 KALAIKUNDA

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KENDRIYA VIDYALAYA SANGATHAN, KOLKATA REGION

PREBOARD EXAMINATION-2020-21

CHEMISTRY (043)

MM: 70

CLASS - XII

TIME ALLOWED: 3 HRS

INSTRUCTIONS

a) There are 33 questions in this question paper. All questions are compulsory.

b) Section A: Q. No. 1-2 are case based questions having four MCQs or Assertion -Reason type

based on given passage each carrying 1 marks and Questions 3 to 16 are MCQs and Assertion–

Reason type questions carrying 1 mark each.

c) Section B: Q. No.17 to 25 are short answer type-I questions and carry 2 marks each.

d) Section C: Q. No.26 to 30 are short answer type-II questions and carry 3 marks each.

e) Section D: Q. No.31 to 33 are long answer questions and carry 5 marks each.

f) There is no overall choice. However internal choices have been provided.

g) Use of calculators and log tables is not permitted.

SECTION – A (Objective Questions)

Passage Based Questions

1. Read the passage given below and answer the following questions

( 1x4 = 4 marks)

Conductivity always decreases with decrease in concentration of both the weak and strong electrolyte. This

is due to the fact that the numbers of ions that carry current in a unit volume of solution always decrease

with decrease in concentration. The conductivity of a solution is the conductance of a unit volume of the

solution, kept between two platinum electrodes with unit area of cross section and at a distance of unit

length. While the molar conductivity is the conductance of that volume of the solution which contains one

mole of the electrolyte.

Conductivity is expressed as G = k = k , ( both A and l are unity in their appropriate units in m or cm ).

While molar conductivity is expressed is

_Ʌ

m

= kV. It is because Ʌ

m

= kA /l

Because L =1 and A = V ( volume containing 1 mole of electrolyte) .

Therefore, Ʌ

m

= k V

Molar conductivity increases with decrease in concentration. This is because the total volume V solution

containing one mole of electrolyte also increases.

In the following questions, two statements Assertion (A) and Reason (R) are given.

a) If A and R both are correct and R is the correct explanation of A.

b) If A and R both are correct and R is not the correct explanation of A.

c) A is true but R is false.

d) A is false but R is true

(i)

Assertion : Conductivity always increases with decrease in concentration for weak and

strong electrolyte

Reason

: Number of ions per unit volume decreases on dilution.

(ii)

Assertion : Conductivity of pure water is 3.5 x 10

-5

_{S/m .}

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(iii)

Assertion : .Conductivity of electrolytes decreases when dissolved in water.

Reason

: They furnish their own ions.

(iv)

Assertion : Conductivity of strong electrolytes decreases on dilution.

Reason

: On dilution number of ions per unit volume decreases.

2. Read the passage given below and answer the following questions

( 1x4 = 4 marks)

Different theories have been put forward to explain the geometries of coordination compounds. Out of

them, the most practical is the valence bond theory which is based upon the concept of hybridisation.

According to this, the complexes with C.N. 4 may be either tetrahedral (sp

3

_{hybridised) or square planar}

(dsp

2

_{hybridised) in nature. Similarly, in the octahedral complexes, the metal atom or ion is either sp}

3

_d

2

hybridised (outer orbital complex) or d

2

_sp

3

_{hybridised (inner orbital complex). Further, these complexes}

may be either paramagnetic if one or more orbitals are half -filled and diamagnetic if all are filled in

nature.

i.

Which is correct in the case of [Fe(CN)

6

]

4-

complex ?

(a) Diamagnetic (b)octahedral (c) d

2

_sp

3

_{hybridised (d) all are correct}

ii.

Which has the highest paramagnetic character?

(a) [Cr(H

2

O)

6

]

3+

(b) [Fe(H

2

O)

6

]

2+

(c) [Cu(H

2

O)

6

]

2+

(d) [Zn(H

2

O)

6

]

2+

iii.

Which statement is correct?

a. [Ni(CO)

4

] : Tetrahedral, paramagnetic

b. [Ni(CN)

4

]

2-

: Square planar, diamagnetic

c. [Ni(CO)

4

] : Tetrahedral, diamagnetic

d. [NiCI

4

]

2-

: Tetrahedral, paramagnetic.

iv.

Both [Ni(CO)

4

] and [Ni(CN)

4

]

2-

are diamagnetic. The hybridisation of nickel in these complexes

respectively are :

(a) sp

3

_{, sp}

3

_{(b) sp}

3

_{, dsp}

2

_{(c) dsp}

2

_{, sp}

3

_{(d) dsp}

2

_{, dsp}

2

Multiple Choice Questions

[1 X 8 = 8 Marks]

Following questions (No.3-11) are multiple choice questions carrying 1 mark each.

3. Which exists as a Zwitter ion?

a. urea b. Acetic acid c. Glycine d. Aniline hydrochloride.

4. Rate law for the reaction A + 2B ---‡ C is found to be

Rate = k [A] [B],

Concentration of reactant ‘B’ is doubled. Keeping the concentration of ‘A’ constant, the value of rate

constant will be :

a. the same b. doubled c. quadrupled d. halved

5. Maximum covalency of nitrogen is :

a. 3

b. 5 c. 4 d. 6

6. The metal which can be used to obtain metallic copper from aqueous CuSO

4

is

a. Na b. Ag c. Hg d. Fe

7. Contribution of each atom per unit cell at face centre in a fcc unit cell is

a. 1 b. 2 c. 0.5 d. 4

8. Diethyl ether is obtained from ethyl alcohol

a. in the presence of H

2

SO

4

at 413 K

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b. in the presence of H

2

SO

4

at 470 K

c. in the presence of H

2

SO

4

at 383 K

d. in the presence of H

2

SO

4

at 273 K

9. Reaction of phenol with chloroform in presence of dilute sodium hydroxide finally introduces which

one of the following functional group?

a. –COOH b. -- CHCI

2

c. ---CHO d. --CH

2

CI

10. Out of following compounds, which will give iodoform test?

(i)Isopropyl alcohol (ii)Isobutyl alcohol (iii)Secondary butyl alcohol (iv)Ethyl alcohol (v) Acetic acid.

a. (i), (ii), (iv) b. (i), (iv) c. (i), (iii), (iv) d. (i), (iv), (v)

11. Which of the following compound is the starting material use for the industrial preparation of phenol

?

a. Cumene b. Anisole c. o-cresol d. Resorcinol

ASSERTION-REASON

[1 X 4 = 4 Marks]

In the following questions(Q.No.12- 16), a statement of Assertion (A )and followed by Reason (R) is

given. Choose the correct answer out of the following choices.

(a) If A and R both are correct and R is the correct explaination of A.

(b) If A and R both are correct and R is not the correct explaination of A.

(c) A is true but R is false.

(d) A is false but R is true

12. Assertion :Carbon oxygen bond length of phenol is slightly less than that of methanol

Reason: There exist a partial double bond character and sp2 – hybridisation of carbon to which

oxygen is attached in phenol.

13. Assertion : Compounds containing -CHO group are easily oxidised to corresponding carboxylic

acids.

Reason

: Carboxylic acids can be reduced to alcohols by treatment with LiAIH4.

14. Assertion : Bond cleavage in haloarene is difficult than haloalkane

Reason

: Phenyl carbocation is more stable than alkyl carbocation.

15. Assertion : A bright silver mirror is produced during the warming of an aldehyde with freshly

prepared ammoniacal silver nitrate solution.

Reason

: A bright silver mirror is produced due to the formation of silver metal.

16. Assertion : Aromatic primary amines cannot be prepared by Gabriel phthalimide synthesis.

Reason: Aryl halides donot undergo electrophilic substitution with anion formed phthalimide.

SECTION –B

Short Answer Type I Questions

(2 X 9 = 18 Marks)

17. What happens , when

(i)Aniline reacts with aqueous solution of bromine in the absence of catalyst ?

(ii)Aniline is treated with acetic anhydride ?

Or

Account for the following :

(i)

pK

b

of aniline is more than that of methylamine

(ii) Ethylamine is soluble in water whereas aniline is not .

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18. Explain why thionyl chloride method is preferred for preparing alkyl chlorides from alcohols ?

19. A first order reaction takes 10 minutes for 25% decomposition. Calculate half life period of the

reaction.

20. Define : (i) Carbylamine reaction

(ii) Hofmann bromamide reaction.

Or

Define : (i) Wurtz -Fittig reaction

(ii) Swarts reaction

21. What is meant by negative deviation from Raoult’s law ? Draw a diagram.

22. Give reason for the following :

A. Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide .

B. Like ammonia , amines are good nucleophiles.

Or

(i) Electron gain enthalpies of halogens are largely negative.

(ii) Thermal stability decreases from H

2

O to H

2

Te

23. What are interstitial compounds? Why are such compounds well known for transition metals?

24. An element ‘A’ crystallises in fcc structure. 200 g of this element has 4.12 x 10

24

_{atoms. The}

density of A is 7.2 g/cm

3

_{. Calculate the edge length of the unit cell.}

25. Explain the following trends in the properties of the members of 3d series.

(a)

Cu

+2

_{ion is not stable in aqueous solution.}

(b)

Mn exhibit maximum number of oxidation states .

SECTION -C

Short Answer Type II Questions

(5 X 3 = 15 Marks)

26. How are the following conversions carried out ?

(i)

Propane to propan-2-ol

(ii)

Benzyl chloride to benzyl alcohol

(iii)

Methyl magnesium bromide to 2- methyl propane-2-ol

27. Give chemical tests to distinguish between :

(i)

Benzaldehyde and acetone.

(ii)

Formic acid and acetic acid

(iii)

Benzoic acid and phenol

Or

(i)

Ethanal and propanal

(ii)

Acetaldehyde and acetone

(iii)

Benzaldehyde and benzoic acid.

28. Write the mechanism of acid dehydration of ethanol to yield ethene.

29. (i) What is meant by Pseudo first order reaction? Give one example.

(ii)Differentiate between order of a reaction and its molecularity.

30. Show how will you synthesise

(i)

Cyclohexyl methanol using an alkyl halide by S

N

2 mechanism?

(ii)

Pentan-1- ol using an alkyl halide?

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SECTION- D

Long Answer Type Questions

(5 X 3 = Marks)

31. Give answer of the following questions.

A. What do you mean by zero order reaction? Write its expression.

B. A reaction is of second order in A and first order in B.

i. Write the differential rate equation.

ii. How is the rate affected on increasing the concentration of A three times?

iii. How is the rate affected when the concentration of both A and B is doubled?

Or

A. What do you mean by first order reaction? Write its expression.

B. In a first order reaction, the reactant concentration decreases from 0.8 M to 0.4 M in 15 min.

What is the time taken for the concentration to change from 0.1 M to 0.0025 M?

32. (i) Write down the electronic configuration of

(a) Cr

3+

_{(b) Cu}

+

_{(c) Co}

2+

_{(d) Mn}

2+

(ii) Describe the cause of the following variations:

(a) Cr

2+

_{is stronger reducing agent than Fe}

2+

_.

(b) E

o

_(M

2+

_{/M) value for copper is positive (+0.34 V)}

(c) Cobalt (II) is stable in aqueous solution but in the presence of complexing reagents, it is

easily oxidised.

Or

i.

Although, Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to

separate them, why?

ii.

Which of the following has the maximum number of unpaired electrons?

Ti

3+

_V

+3

_Fe

2+

_Zn

2+

iii.

Give two consequences of lanthanoid contraction.

iv.

Based on the data, arrange Fe

2+

_{, Mn}

2+

_{and Cr}

2+

_{in the increasing order of stability of +3}

oxidation state

[E

o

(Cr3+ /Cr +2 )

= - 0.4 V ; E

o

(

Mn3+ /Mn +2 )

= 1.5 V ; E

o(Fe3+ / Fe 2+

= 0.8 V ]

33. (i) Henry’s law constant for CO

2

in water is 1.67 x 10

8

Pa at 298 K. Calculate the quantity of CO

2

,

in 500 m L of soda water when packed under 2.5 atm CO

2

pressure at 298K .

(ii)Calculate the mass of the compound (molar mass = 256 g/mol) to be dissolved in 75 g of benzene

to lower its freezing point by 0.48 K. (K

f

= 5. 12 K kg /mol)

Or

A solution containing 30 g of a non- volatile solute exactly in 90 g of water has a vapour pressure of

2.8 kPa at 298 K. Further, 18 g of water is then added to the solution and the new vapour pressure

becomes 2.9 kPa at 298 K .

Calculate: (i) Molar mass of the solute.

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KENDRIYA VIDYALAYA, Kolkata region Class: XII Session: 2020-21

Computer Science (083) PREBOARD EXAM (Theory)

Maximum Marks: 70 Time Allowed: 3 hours

General Instructions:

1. This question paper contains two parts A and B. Each part is compulsory. 2. Both Part A and Part B have choices.

3. Part-A has 2 sections:

a. Section – I is short answer questions, to be answered in one word or one line.

b. Section – II has two case studies questions. Each case study has 4 case-based sub-parts. An examinee is to attempt any 4 out of the 5 subsub-parts.

4. Part - B is Descriptive Paper. 5. Part- B has three sections

a. Section-I is short answer questions of 2 marks each in which two question have internal options.

b. Section-II is long answer questions of 3 marks each in which two questions have internal options.

c. Section-III is very long answer questions of 5 marks each in which one question has internal option.

6. All programming questions are to be answered using Python Language only

Question Part-A Marks

No. allocated

Section-I

Select the most appropriate option out of the options given for each question. Attempt any 15 questions from question no 1 to 21.

1 Find the invalid identifier from the following 1

a) yourName b) _false c) 2My_Name d) My_Name

2 Given the lists L=[1,3,6,82,5,7,11,92] , write the output of print(L[1:6]) 1

3 Rearrange the following terms in increasing order of data transfer rates. 1

Gbps, Mbps, Tbps, Kbps, Bps

4 Which of the following is a valid assignment operator in Python ? 1 a) ? b) < c) =* d) and e) //

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5 Suppose a tuple T is declared as T = (10, 12, 43, 39), which of the following is 1 incorrect? a) print(T[1]) b) T[3] = 9 c) print(max(T)) d) print(len(T))

6 Write a statement in Python to declare a dictionary whose keys are 1, 2, 3 1 and values are Monday, Tuesday and Wednesday respectively.

7 A tuple is declared as 1

T = (2,5,6,9,8)

What will be the value of sum(T)?

8 Name the built-in mathematical function / method that is used to return an 1 absolute value of a number.

9 Name the protocol that is used to send emails. 1

10 Your friend Ranjana complaints that somebody has created a fake profile on 1 Facebook and defaming her character with abusive comments and pictures. Identify the type of cybercrime for these situations.

11 In SQL, name the clause that is used to display the tuples in ascending order 1 of an attribute.

12 In SQL, what is the use of IS NULL operator? 1

13 Write any one aggregate function used in SQL. 1

14 Which of the following is a DDL command? 1

a) SELECT b) ALTER c) INSERT d) UPDATE

15 Name The transmission media best suitable for connecting to hilly areas. 1

16 Identify the valid declaration of L: 1

L = [‘Mon’, ‘23’, ‘hello’, ’60.5’]

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a. dictionary b. string c.tuple d. list

17 If the following code is executed, what will be the output of the following 1 code?

name="ComputerSciencewithPython" print(name[3:10])

18 In SQL, write the query to display the list of tables stored in a database. 1

19 Write the expanded form of Wi-Fi. 1

20 Which of the following types of table constraints will prevent the entry of 1 duplicate rows? a) check b) Distinct c) Primary Key d) NULL 21 1

Write the full form of CSV.

Section-II

Both the Case study based questions are compulsory. Attempt any 4 sub parts from each question. Each question carries 1 mark

22 A departmental store MyStore is considering to maintain their inventory using SQL to store the data. As a database administer, Abhay has decided that :

• Name of the database - mystore • Name of the table - STORE

• The attributes of STORE are as follows: ItemNo - numeric

ItemName – character of size 20 Scode - numeric

Quantity – numeric

(17)

Table : STORE

ItemNo ItemName Scode Quantity

2005 Sharpener Classic 23 60

2003 Ball Pen 0.25 22 50

2002 Get Pen Premium 21 150

2006 Get Pen Classic 21 250

2001 Eraser Small 22 220

2004 Eraser Big 22 110

2009 Ball Pen 0.5 21 180

(a) Identify the attribute best suitable to be declared as a primary key, 1 (b) Write the degree and cardinality of the table STORE. 1 (c) Insert the following data into the attributes ItemNo, ItemName and 1

SCode respectively in the given table STORE.

ItemNo = 2010, ItemName = “Note Book” and Scode = 25

(d) Abhay want to remove the table STORE from the database MyStore. 1 Which command will he use from the following:

a) DELETE FROM store; b) DROP TABLE store;

c) DROP DATABASE mystore; d) DELETE store FROM mystore;

(e) Now Abhay wants to display the structure of the table STORE, i.e, 1 name of the attributes and their respective data types that he has

used in the table. Write the query to display the same.

23 Ranjan Kumar of class 12 is writing a program to create a CSV file “user.csv” which will contain user name and password for some entries. He has written the following code. As a programmer, help him to successfully execute the given task.

import _____________ # Line 1

def addCsvFile(UserName,PassWord): # to write / add data into the

CSV file

f=open(' user.csv','________') # Line 2

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newFileWriter = csv.writer(f)

newFileWriter.writerow([UserName,PassWord]) f.close()

#csv file reading code

def readCsvFile(): # to read data from CSV file with open(' user.csv','r') as newFile:

newFileReader = csv._________(newFile) # Line 3 for row in newFileReader:

print (row[0],row[1]) newFile.______________ # Line 4 addCsvFile(“Arjun”,”123@456”) addCsvFile(“Arunima”,”aru@nima”) addCsvFile(“Frieda”,”myname@FRD”) readCsvFile() #Line 5

(a) Name the module he should import in Line 1. 1

(b) In which mode, Ranjan should open the file to add data into the file 1 (c) Fill in the blank in Line 3 to read the data from a csv file. 1 (d) Fill in the blank in Line 4 to close the file. 1 (e) Write the output he will obtain while executing Line 5. 1

Part – B Section-I

24 Evaluate the following expressions: 2

a) 6 * 3 + 4**2 // 5 – 8

b) 10 > 5 and 7 > 12 or not 18 > 3

25 Differentiate between Viruses and Worms in context of networking and data 2 communication threats.

OR

Differentiate between Web server and web browser. Write any two popular web browsers.

26 Expand the following terms: 2

a. SMTP b. XML c. LAN d. IPR

(19)

27 Differentiate between actual parameter(s) and a formal parameter(s) with a 2 suitable example for each.

OR

Explain the use of global key word used in a function with the help of a suitable example.

28 Rewrite the following code in Python after removing all syntax error(s). 2 Underline each correction done in the code.

Value=30

for val in range(0,Value) If val%4==0: print (val*4) Elseif val%5==0: print (val+3) Else print(val+10)

29 What possible outputs(s) are expected to be displayed on screen at the time 2 of execution of the program from the following code? Also specify the

maximum values that can be assigned to each of the variables Lower and Upper.

import random

AR=[20,30,40,50,60,70]; Lower =random.randint(1,3) Upper =random.randint(2,4) for K in range(Lower, Upper +1):

print (AR[K],end=”#“)

(i) 10#40#70# (ii) 30#40#50# (iii) 50#60#70# (iv) 40#50#70#

30 What do you understand by Candidate Keys in a table? Give a suitable 2 example of Candidate Keys from a table containing some meaningful data.

(20)

31 2 32 Write the full forms of DDL and DML. Write any two commands of DML in 2

SQL.

33 Find and write the output of the following Python code: 2 def Display(str): m="" for i in range(0,len(str)): if(str[i].isupper()): m=m+str[i].lower() elif str[i].islower(): m=m+str[i].upper() else: if i%2==0: m=m+str[i-1] else: m=m+"#" print(m) Display('Fun@Python3.0') Section- II

34 Write a function LShift(Arr,n) in Python, which accepts a list Arr of numbers 3 and n is a numeric value by which all elements of the list are shifted to left.

Sample Input Data of the list Arr= [ 10,20,30,40,12,11], n=2 Output

Arr = [30,40,12,11,10,20]

35 Write a function in Python that counts the number of “Me” or “My” words 3 present in a text file “STORY.TXT”.

If the “STORY.TXT” contents are as follows: My first book

was Me and

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My Family. It gave me chance to be Known to the world.

The output of the function should be: Count of Me/My in file: 4

OR

Write a function AMCount() in Python, which should read each character of a text file STORY.TXT, should count and display the occurance of alphabets A and M (including small cases a and m too). Example:

If the file content is as follows: Updated information

As simplified by official websites.

The EUCount() function should display the output as: A or a:4

M or m :2

Write the outputs of the SQL queries (i) to (iii) based on the relations Teacher 3 and Posting given below:

Table : Teacher

T_ID Name Age Department Date_of_join Salary Gender 1 Jugal 34 Computer Sc 10/01/2017 12000 M 2 Sharmila 31 History 24/03/2008 20000 F 3 Sandeep 32 Mathematics 12/12/2016 30000 M 4 Sangeeta 35 History 01/07/2015 40000 F 5 Rakesh 42 Mathematics 05/09/2007 25000 M 6 Shyam 50 History 27/06/2008 30000 M 7 Shiv Om 44 Computer Sc 25/02/2017 21000 M 8 Shalakha 33 Mathematics 31/07/2018 20000 F Page 8 of 11

(22)

Table : Posting

P_ID Department Place

1 History Agra

2 Mathematics Raipur

3 Computer Science Delhi

i. SELECT Department, count(*) FROM Teacher GROUP BY Department;

ii. SELECT Max(Date_of_Join),Min(Date_of_Join) FROM Teacher;

iii. SELECT Teacher.name,Teacher.Department, Posting.Place FROM Teachr, Posting WHERE Teacher.Department = Posting.Department AND Posting.Place=”Delhi”;

37 Write a function in Python PUSH(Arr), where Arr is a list of numbers. From 3 this list push all numbers divisible by 5 into a stack implemented by using a

list. Display the stack if it has at least one element, otherwise display appropriate error message.

OR

Write a function in Python POP(Arr), where Arr is a stack implemented by a list of numbers. The function returns the value deleted from the stack.

Section-III

38 MyPace University is setting up its academic blocks at Naya Raipur 5 and is planning to set up a network. The University has 3 academic

blocks and one Human Resource Center as shown in the diagram below:

Center to Center distances between various blocks/center is as follows:

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Law Block to business Block 40m Law block to Technology Block 80m Law Block to HR center 105m Business Block to technology

30m Block

Business Block to HR Center 35m Technology block to HR center 15m

Law Block 15

Technology Block 40

HR center 115

Business Block 25

a)Suggest the most suitable place (i.e., Block/Center) to install the server of this University with a suitable reason.

b)Suggest an ideal layout for connecting these blocks/centers for a wired connectivity.

c)Which device will you suggest to be placed/installed in each of these blocks/centers to efficiently connect all the computers within these blocks/centers.

d)

Suggest the placement of a Repeater in the

network with justification.

e)The university is planning to connect its admission office in Delhi, which is more than 1250km from university. Which type of network out of LAN, MAN, or WAN will be formed? Justify your answer.

39 Write SQL commands for the following queries (i) to (v) based on the 5 relations Teacher and Posting given below:

Name Age Department Date_of_join Salary Gender

Jugal 34 Computer 10/01/2017 12000 M

Sc

Sharmila 31 History 24/03/2008 20000 F

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3 Sandeep 32 12/12/2016 30000 M 4 Sangeeta 35 History 01/07/2015 40000 F 5 Rakesh 42 05/09/2007 25000 M 6 Shyam 50 History 27/06/2008 30000 M 7 Shiv Om 44 Computer 25/02/2017 21000 M Sc 8 Shalakha 33 31/07/2018 20000 F Table : Posting Department Place 1 History Agra 2 Mathematics Raipur

3 Computer Science Delhi i. To show all information about the teacher of

History department.

ii. To list the names of female teachers who are in Mathematics department.

iii. To list the names of all teachers with their date of joining in ascending order.

iv. To display teacher’s name, salary, age for male teachers only. v. To display name, bonus for each teacher where bonus is 10%

of salary.

5 A binary file “Book.dat” has structure [BookNo, Book_Name, Author, Price].

i. Write a user defined function CreateFile() to input data for a record and add to Book.dat .

ii. Write a function CountRec(Author) in Python which accepts the Author name as parameter and count and return number of books by the given Author are stored in the binary file “Book.dat”

OR

A binary file “STUDENT.DAT” has structure (admission_number, Name, Percentage). Write a function countrec() in Python that would read contents of the file “STUDENT.DAT” and display the details of those students whose percentage is above 75. Also display number of students scoring above 75%

(25)

KENDRIYA VIDYALAYA KOLKATA REGION

Pre-Board Examination

Class: XII Session: 2020-21

Subject: Mathematics

Time Allowed: 3 Hours Maximum Marks: 80 General Instructions:

1. This question paper contains two parts A and B. Each part is compulsory. Part A carries 24 marks and Part B carries 56 marks.

2. Part-A has Objective Type Questions and Part -B has Descriptive Type Questions. 3. Both Part A and Part B have choices.

Part – A:

1. It consists of two sections- I and II.

2. Section I comprises of 16 very short answer type questions.

3. Section II contains 2 case studies. Each case study comprises of 5 case-based MCQs. An examinee is to attempt any 4 out of 5 MCQs.

Part – B:

1. It consists of three sections- III, IV and V.

2. Section III comprises of 10 questions of 2 marks each. 3. Section IV comprises of 7 questions of 3 marks each. 4. Section V comprises of 3 questions of 5 marks each.

5. Internal choice is provided in 3 questions of Section –III, 2 questions of Section-IV and 3 questions of Section-V. You have to attempt only one of the alternatives in all such questions.

Sr. No.

Part – A

Marks

Section I

All questions are compulsory. In case of internal choices

attempt any one.

1 Check whether the function : → defined as ( )

= cos for

all

_{∈ is one-one or not.}

1

2 A relation R in = {1,2,3} is defined as = { (1,1 ), (2,2), (3,3),

_{(1,2), (2,3)}, then show that R is reflexive but neither symmetric}

nor transitive.

1

3 If

R = {(a, a ): a is a prime number less than 7} be a relation .

(26)

OR

Find the total number of functions from the set

_{A = {2, 4, 6, 8, 10}}

to the set

_{B = {p, q, r}.}

4 Write the element

of a

3 × 3 matrix =

, whose element

are given by

₌

| |

.

1

5 _Find

_,

_{= 3 2}

1 4

and

2 + = 1

−3 2

0

1

6 If is a matrix of order 3 such that

₍

_{) = 10 . Then, find the}

value of

|

|.

OR

If is a skew-symmetric matrix, then find whether

is

symmetric or skew-symmetric.

1

7 Evaluate ∫

√

.

OR

Evaluate ∫ (

−

)

.

1

8 Find the area of the parabola

= 4

bounded by its latus

rectum.

1

9 The function

_{( ) = [ ], where [ ] denotes the greatest integer}

function, then discuss the continuity of

_{( ) .}

OR

How many arbitrary constants are there in the particular solution

of a differential equation of third order?

1

10 If

⃗ = 7 ̂ + ̂ − 4

⃗ = 2 ̂ + 6 ̂ + 3 , then find the projection

of

_⃗

⃗ .

1

11 Find the value of the expression

_{⃗ × ⃗ + ⃗ . ⃗ .}

OR

If a line makes angles

_,

with

_,

₋

_,

respectively, then find direction cosines.

1

12 Find the area of a parallelogram whose adjacent sides are

represented by the vectors

_{2 ̂ − 3}

_{4 ̂ + 2 .}

1

13 Find the distance of the point

(2, 3, −5) from the plane + 2 −

(27)

14 For any two vectors

⃗

⃗,

⃗ ⊥

⃗, ℎ

ℎ

⃗ . ⃗

1

15 If A and B are two independent events, then write

( ∩ ) in

terms of P(A) and P(B) .

1

16 Let and be the events associated with the sample space ,

then find the value of

( ⁄ ) .

1 Section II

Both the Case study based questions are compulsory.

Attempt any 4 sub parts from each question (17-21) and

(22-26). Each question carries 1 mark.

17 In a bolt factory, machines A, B and C manufacture respectively

25% , 35% and 40% of the total bolts. Of their output 5% , 4%

and 2% are respectively defective bolts.

On the basis of above information answer the following

(i) The probability that bolt drawn is defective given that bolts is

manufactured by B is

(a) 0.05

(b) 0.04

(c) 0.02

(d) 0.01

1 (ii) The probability that, if drawn bolt is defective, then it is

manufactured by B is

(a)

_{14 69}

⁄

(b)

_{17 69}

⁄

(c)

_{19 69}

_⁄

(d)

_{28 69}

⁄

1 (iii) The total probability of drawn bolt is defective, is

(a) 0.0355

(b) 0.0345

(c) 0.0534

(d)0.0435

1 (iv) If drawn bolt is defective, then the probability that it is not

manufactured by

(a)

_{40 69}

⁄

(28)

(b)

_{39 69}

_⁄

(c)

_{42 69}

⁄

(d)

_{41 69}

⁄

(v) Let ,

_,

be the event that bolt is manufactured by

, , respectively and

be the event that drawn bolt is

defective, then the value of

∑

(

⁄ is

)

(a) 3

(b) 2

(c) 0

(d) 1

1

18 A square piece of tin of side 24 cm is to be made into a box

without top by cutting a square from each corner and folding up

the flaps to form a box

(i) The length, breadth and height of the box formed, in terms of

are

(a)

_{(24 − 2 , , 24 − 2 )}

(b)

_{(24 − 2 , 24 − 2 , )}

(c)

_{( , 24 − 2 , 24 − 2 )}

(d)

_{( , , )}

1 (ii) Volume V of the box expressed in terms of is

(a)

_{(24 − 2 )}

(b)

(c)

_{(24 − 2 )}

(d)

_{(24 − 2 )}

1 (iii) Maximum value of volume of box is

(a)

₂₅₆

(b)

₅₁₂

(c)

₁₀₂₄

(d)

₂₀₄₈

(29)

(iv) The value of when volume is maximum, is

(a)

₁₂

(b)

₈

(c)

₄

(d)

₂

1 (v) The cost of box, if rate of making the box is Rs. 5 per

,

when volume is Maximum, is

(a)

_{. 3840}

(b)

_{. 2840}

(c)

_{. 2040}

(d)

_{. 3480}

1 Part – B

Section III

All questions are compulsory. In case of internal choices

attempt any one.

19 _{Find the domain of}

_{sec (2 + 1) .}

2

20 Show that the points

_{( + 5, − 4), ( − 2, + 3)}

_{( , ) do}

not lie on a straight line for any value of

_.

OR

If

₌

2 ₂

0 ₁

1 ₃

1 −1 0

, then find the value of

_{− 5 .}

2

21 Find the value of for which

( ) =

_{− 1,}

+ 5,

ℎ

_ℎ

≤ 2

_{> 2}

is continuous at

_{= 2 .}

2

22 Show that the function

( ) = 4 − 18 + 27 − 7 has neither

maxima nor minima.

2

23 Evaluate ∫ (1 − )

_OR

Evaluate ∫ [ ] , where [. ] is the greatest integer function.

2

24 Find the point on the curve

= 2 − 6 − 4 at which the

(30)

25 _Solve

_{( − 1) = 2}

_.

2

26 Show that the area of a parallelogram having diagonals

3 ̂ + ̂ −

2 and ̂ − 3 ̂ + 4 is 5√3 sq units.

2

27 The

−coordinate of a point on the line joining the points

(2, 2, 1) and (5, 1, −2) is 4. Find its −coordinate.

2

28 One card is drawn at random from a pack of well- shuffled deck

of cards.

Let

_{: the card drawn is a spade}

: the card drawn is an ace

Are the events

indepebdent?

OR

If

_{( ) = , ( ) = and ( ∩ ) = , find}

⁄

.

2 Section IV

All questions are compulsory. In case of internal choices

attempt any one.

29 Let

= − {3}, = − {1}. If : → be defined by

( ) =

, ∀ ∈ . Show that is bijective.

3

30 _{Evaluate ∫}

( )

.

3

31 _If

₌

_{, > 0 then find .}

3

32 Find the particular solution of the differential equation

(1 +

)

+ (1 + )

= 0 , given that = 1 when = 0 .

3

33 Find the area bounded by the curve

_{= 4 ( − 1) and the}

lines

_{= 1 and = 4 .}

OR

Find the area bounded by the ellipse

_{+ = 1 and the}

ordinates

_{= 0}

_{= , where, = (1 − ) and < 1 .}

3

34 Find the intervals in which the function given by

_{( ) =}

₊

_{, 0 ≤ ≤ 2 is}

a) strictly increasing b) strictly decreasing

3

35 Prove that the greatest integer function defined by ( ) = [ ], 0 <

(31)

OR

If

₌

, then prove that

−

1 − = 0

Section V

All questions are compulsory. In case of internal choices

attempt any one.

36 If

₌

1 −1

_{1 −2 −2}

1

2

1

3 and

=

−4

4

4 −7

1

3

5 −3 −1

, find

. Use this

to solve the system of equations

− + = 4 , − 2 − 2 = 9 and 2 + + 3 = 1 .

OR

If

₌

1 −1

₂

₁

₋₃

1

1 ,

find

and hence solve the system of linear equation

+ 2 + = 4 , − + + = 0 , − 3 + = 2 .

5

37 Find the shortest distance between the lines given by

⃗ = (2 +⋋) ̂ − (3 +⋋) ̂ + (5 +⋋)

and

_{⃗ = (2 − 1) ̂ +}

(4 − 1) ̂ + (5 − 3 ) .

OR

Find the equation of the plane which contains the line of

intersection of the planes

_{⃗ ̂ − 2 ̂ + 3 − 4 = 0}

and

⃗ −2 ̂ + ̂ +

+ 5 = 0 and whose intercept on -axis is equal to

that of on Y-axis .

5

38 Solve the following linear programming problem (L.P.P)

graphically.

Minimize = 5 + 10 , subject to the constraints ;

+ 2 ≤ 120, + ≥ 60, - 2 ≥ 0, and , ≥ 0

OR

Solve the following linear programming problem (L.P.P)

graphically. Maximize = 8 + 9 , subject to the constraints ;

2 + 3 ≤ 6, 3 - 2 ≤ 6, ≤ 1, and , ≥ 0.

(32)

1 | P a g e

KENDRIYA VIDYALAYA SANGATHAN , KOLKATA REGION

Pre-Board Question Paper (Theory)

Class: XII Session: 2020-2021

Subject: Physics [042]

Maximum Marks: 70Marks Time Allowed: 3hours

General Instructions:

(1) All questions are compulsory. There are 33 questions in all.

(2) This question paper has five sections: Section A, Section B, Section C, Section D and Section E.

(3) Section A contains ten very short answer questions and four assertion

reasoning MCQs of 1 mark each, Section B has two case based questions of 4 marks each, Section C contains nine short answer questions of 2 marks each, Section D contains

fiveshortanswerquestionsof3markseachandSectionEcontainsthreelonganswer questions of 5 marks each.

(4) There is no overall choice. However internal choice is provided. You have to attempt only one of the choices in such questions.

Section – A

Sr.No. All questions are compulsory. In case of internal choices, attempt any one of them.

Marks

1 Is electric flux a scalar or a vector? 1

2 Predict the direction of induced current In a metal ring when the ring is moved Toward a straight conductor with constant

speed v. The conductor is carrying a constant current in the direction shown in the figure.

1

3 How does the angle of minimum deviation of a glass prism vary if the incident violet light is replaced by red light?

OR

What are the direction of electric and magnetic field vectors relative to each other and relation to the direction of propagation of electromagnetic waves?

1

4

How does the angular separation of interference fringes changes in Young’s experiment, if the distance between the slits is increased?

1

5 What is the value of angular momentum of electron in the second orbit of Bohr’s model of hydrogen atom?

1 6 In a tropical nuclear reaction e.g. , ₊ _→ ₊ _{+ 3.27}

,although number of nucleons is conserved , yet energy is released. How?

1 v

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2 | P a g e

7 How does the width of a depletion region of a p-n junction vary if doping concentration is increased?

1 8 In half wave rectification, what is the output frequency if input frequency

is 25 Hz.

1 9 9 State the factors on which the refractive index of a material medium for a

given wavelength depends.

1 11 10 Two lenses of power 3D and -5D are in combination, finf the effective

focal length of this combination.

1 For question numbers 11,12,13and14,two statements are given-one

labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

a) Both A and R are true and R is the correct explanation of A b) Both A and R are true but R is NOT the correct explanation of A c) A is true but R is false

d) A is false and R is also false 11

Assertion(A):

A charged particle free to move in an electric field always moves along an electric field line.

Reason(R):

The electric field lines diverge from a negative charge and converge at positive charge.

1

12 Assertion(A):

A parallel plate capacitor is connected across battery through a key. A dielectric slab of dielectric constant K is introduced between the plates. The energy which is stored becomes K times.

Reason(R):

The surface density of charge on the plate remains constant or unchanged.

1

13 Assertion (A):

A ray of light is incident from outside on a glass sphere surrounded by the air. This ray may suffer total internal refraction at the second interface.

Reason (R):

If a ray of light goes from denser to rarer medium, it bends away from the normal.

1

14 Assertion(A):

A convex lens of focal length 30 cm can’t be used as a simple microscope in normal setting.

Reason (R):

For normal setting, the angular magnification of simple microscope is M=D/f

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3 | P a g e

Section – B

Q Questions 15 and 16 are Case Study based questions and are compulsory. Attempt all 3 sub parts from each question.

15

A group of students while coming from school noticed a box marked “Danger H.T 2200 V” at a substation in the main street.They did not understand the utility of such a high voltage ,while they argued, the supply was only 220 V.They asked their teacher this question the next day.The teacher thought it to be an important question and therefore explained to the whole class.

(a) What device is used to bring the high voltage down to low voltage of A.C current and what is the principle of its working?

(b) Is it possible to use this device for bringing down the high D.C voltage to the low voltage ? Explain

(c) Write the value displayed by the students and the teacher.

4

16 Asha’s uncle was adviced by his doctor to have an MRI( Magnetic Resonance Imaging ) scan of his brain .Her uncle felt that it was too expensive and wanted to postpond it.When Asha learnt about this , she took the help of her family and when she approached the doctor,he also offered a substantial discount .She thus convinced her uncle to undergo the test to enable the doctor to know the condition of his brain. The resulting information greatly helped his doctor to treat him properly. Based on the above paragraph , answer the following questions:

a) What according to you are the values displayed by Asha,her family and Doctor.

b) What in your view could be the reason for MRI test to be so expensive ?

c) Assuming that MRI test was performed using a magnetic field of 0.1 T,find the maximum and minimum values of the force that the magnetic field could exert on a proton (charge _{= 1.6 × 10} C)that was moving with a speed of _{10 / .}

44 4

Section – C

All All questions are compulsory. In case of internal choices, attempt anyone.

17

Deduce Coulomb’s law from Gauss’s theorem. OR

A cylinder is placed in a uniform electric field ⃗ with its axis parallel to the field.Show that the total electric flux through the cylinderis zero.

(35)

4 | P a g e

18 Show mathematically that the potential at a point on the equatorial line of an electric dipole is zero.

2

19 Why does the capacitance of a conductor increase, when an earthed connected conductor is placed near it? Briefly explain.

OR

Three capacitors _{= 10 ,} _{= 5} _{= 5} are connected to a 6V battery, as shown in fig. Find the charges on the three capacitors.

2

20 If the horizontal component of earth’s magnetic field at a place where the angle of dip is _{60 is 0.4 × 10} , calculate the vertical component and the resultant magnetic field at that place.

2

21 Use Biot-Savart law to obtain an expression for the magnetic field at the centre of a coil bent in the form of a square of side 2a currying current _.

22 2 22 Arrange the following electromagnetic waves in the order of their

increasing wavelength:

a) γ – rays b) Microwaves c) X- rays d) Radio waves.

What role does infra-red radiation play in maintaining the Earth’s warmth?

22 2

23 A region is illuminated by two sources of light. The intensity at each point is found to be equal to _{+ , where is the intensity of light at the} point when source 2 is absent. is similarly defined. Are the sources coherent or incoherent? Explain.

OR

Draw the diagram showing intensity distribution of light on the screen for diffraction of light at a single slit. How is the width of central maxima affected if (i) the width of the slit is doubled; (ii) the wavelength of the light used is increased?

22 2

24 _{Draw reverse characteristics of a junction diode. Why do we get reverse} saturation current?

2

25 An electron and a proton each have the same de-Broglie wavelength. Which one of these has higher kinetic energy? Which one is moving faster?

2 6 V

(36)

5 | P a g e

OR

Plot a graph showing variation of de-Broglie wavelength versus √ ,where V is accelerating potential for two particles A and B carrying same charge but of masses _, ( _> ). Which one of the two (A or B) represents a particle of smaller mass and why?

Section -D

Q Questions are compulsory. In case of internal choices, attempt anyone.

26 _{Two free point charges}_{+4 and + are placed a distance “a” apart.} Where should a third point charge q be placed between them such that the entire system may be in equilibrium? What should be the magnitude of q? What type of an equilibrium will it be?

OR

An electric dipole of dipole moment _{⃗is placed in a uniform electric field} ⃗.Show diagrammatically the orientation of the dipole in the field for which the torque is (i) maximum (ii)half the maximum value (iii) zero.

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27 A ray of light goes from medium 1 to medium 2. Velocities of light in the two media are respectively. For an angle of incidence in medium 1, the corresponding angle of refraction in medium 2 is _{/2 .}

(i) Which of the two media is optically denser and why? (ii) Establish the relationship between _, .

OR

Two monochromatic waves emanating from two coherent sources have the displacements represented by _{= cos} ,and _{= cos( + ),} where is the phase difference between the two displacements. Show that the resultant intensity is given by _{= 4} _{( ) where ∝}

.Hence obtain the conditions for constructive and destructive interference.

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28

Figure shows a rectangular conducting loop PQRS in which arm QR of length “ ” has movable. The loops kept in a uniform magnetic field “B” directed downward perpendicular to the plane of the loop.The arm QR is moved with a uniform speed “ _".

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Deduce the expression for:

(i) the emf induced across the arm “QR”

(ii) the external force required to move the arm, and the power dissipated as heat.

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29 A 12.9 eV beam of electrons is used to bombard gaseous hydrogen at room temperature. Up to which energy level the hydrogen atoms would be excited? Calculate the wavelength range of Paschen series.

3

30 _{Draw a circuit diagram of a full wave rectifier. Explain its working principle.} Draw the input/output, wave forms indicating clearly the functions of the two diodes used.

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Section – E

All questions are compulsory. In case of internal choices, attempt anyone.

31 Define the terms (i) ‘cut-off voltage’ and (ii) ‘threshold frequency’ in relation to the phenomenon of photoelectric effect.

Using Einstein’s photoelectric equation show how the cut-off voltage and threshold frequency for a given photosensitive material can be determined with the help of a suitable plot/graph.

OR

(a) Consider two different hydrogen atoms. The electron in each atom is in an excited state. Is it possible for the electrons to have different energies but same orbital angular momentum according to the Bohr model? Justify your answer.

( b) Obtain an expression for the frequency of radiation emitted when a hydrogen atom de-excites from level n to level (n-1).For large n, show that this frequency equals the classical frequency of revolution of the electron in the orbit .

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P Q

R S

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32 a) Derive the expression for the current flowing in an ideal

inductor and its reactance when connected to an ac source of emf €=€0sinωt.

b) Draw its phasor diagram.

c) If resistance is added in series to inductor what changes will occur in the current flowing in the circuit and phase angle between voltage and current.

OR

In series LCR circuit connected to an ac source of variable frequency and emf €=€0sinωt , draw a plot showing the variation of current ( ) with

angular frequency (ω) for two different values of resistance

( > ).Write the condition under which the phenomenon of resonance occurs. For which value of the resistance out of the two curves, a sharper resonance is produced? Define Q-factor of the circuit and gives its

significance.

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33

(a) Define fringe width. Calculate the value of fringe width (for bright fringe only) using Young’s double slit experiment, draw required diagram.

(b) Explain two advantages of a reflecting telescope over a refracting telescope.

OR

(a)There are two sets of apparatus of Young’s double slit experiment. In set A, the phase difference between the two waves emanating from the slits does not change with time, whereas in set B, the phase difference between the two waves from the slits changes rapidly with time. What difference will be observed in the pattern obtained on the screen in the two set up’s?

(b) Deduce the expression for the resultant intensity in both the above-mentioned set ups (A and B), assuming that the waves emanating from the two slits have the same amplitude A and same wavelength λ.