Which of the following is correct? -

| IIT-JEE 2006

35. Which of the following is correct?

(a) B(OCH3)3 is much weaker Lewis acid than BBr3

(b) B(OH)3 {aq) behaves as a triprotic acid (c) [H,B03]~ („(/) is a conjugate base of H3B03 (u</)

(d) all of the above.

PASSAGE 2 : Read the following passage and answer the questions numbered 36 to 40. They have only one correct option.

In presence of metal catalyst (Ni, Pt, Pd) hydrogen adds to a "^C = C < and - C = C - bonds. The metal catalysts are used in finely divided state in solvent like ethanol. These are classified as heterogenous catalysts.

Both H, and alkene get absorbed at the surface of metal.

The less crowded alkene adsorbs with faster rate. Both breaking of 7t-bond of alkene and a bond of H, take place at metal surface. Hydrogenation reactions are exothermic in nature. If palladium is precipitated at the surface of calcium carbonate and it is treated with quinoline it becomes deactivated for adsorption of alkenes.

But it can effectively catalyse hydrogenation of - C = C - . The alkyne can adsorb at the surface of poisoned metal catalyst and syn addition of hydrogen atoms take place. The relative rate of hydrogenation follows the order:

- C = C - > / C = C < > / C = 0 > C6H(, If sodium or lithium metals dissolved in liquid ammonia are used with alkynes then the metal transfers its electrons to7i-frameworkof-C = C - b o n d and an anion radical is formed, Liquid ammonia provides H atom and a vinylic radical is formed. The process is repeated and an anti addition of H atoms occurs at - C = C - bond. A

C H E M I S T R Y T O D A Y | FEBRUARY '06 160

vinyl carbanion / C = C ^ is more stable than

^ C — C — .So only alkynes (nonterminal) are reduced by this method and not alkenes (nonterminal).

36. Which of the following involves homogeneous reduction?

HJNi.

(a) CH, = CH, C H3 - CLI,

(b) C H3- C E H C - C H3

CH, - CH— CH - CH, + NaNH,

H2/Pd/CaC03/quinoline

> CHjCHO

( c ) C H 3 C O C I

H,/Pd/BaSO,/quinoline

(d) CH,C = CH — 2 > C H3C H = C H2

37. The relative rate of catalytic hydrogenation of following alkenes is

C X N_ W

(I) (II) (III) (IV) (a) I > IV > 111 > II (b) II > III > IV > I (c) HI > IV > I > II (d) II > IV > 1 > III.

38. The product of following reaction is O

Pd-CaC03-quinoline

(a) h (b)

( 0

( V ^

^W⁰

_{JJ I}

39. The product of following reaction is / ^(CH²),\ / C H ,

o Na, NH, „ n - C4H, ( C H , ) /

(a) a mixture of four stereoisomers

(b) a mixture of cis, cis and trans, trans isomers (two stereoisomers)

(c) a mixture of cis, trans and trans, cis isomers (two stereoisomers)

(d) a single stereoisomer (cis, trans).

40. In which case the reaction is most exothermic with H2/Ni?

(a)

(c)

(b)

(d)

One or more than one options may be correct (for Q. 41 to 55)

41. In which of the following pairs hybridisation of the central atom is same?

(a) C1F3, C1F30 (b) C1F30, CIF302

(c) [C1F20]+, [ClF40r (d) [C1F40]-, [XeOF4], 42. There are three elements P, O and R which belong to p-block of the periodic table they all form trifluorides with F2, such that PF-, is Lewis acid but 0F3 is a weaker Lewis base (dipole moment = 0.23 D). These two compounds react with each other in presence of F2 to produce C?F4+ PF4_. The compound ^F3 is a T-shape in interhalogen molecule. Which of the following is/are correct statements with reference to above informations?

(a) all the R- F bond lengths are equal in RF3 molecule

(b) in the structure the angle 0 * 1 8 0 °

(c) the O and P both are sp3 hybridised in the salt OF4+PF4"

(d) the elements P, O and R can be B, N and Cl respectively.

43. On the basis of structure of graphite, which of the following is/are true for it?

(a) it is a diamagnetic substance

(b) it behaves like metallic as well as semiconductor (c) it is less dense than diamond

(d) it reacts with F2 to form product which is more conducting than graphite.

44. Which of the following is correct about B2H6? (a) each B atom is sp3 hybridised

(b) it consists of two - "3 centre 2 electron bonds"

(d) all of the above.

45. Given that interionic distance in Na+F~ crystal is 2.31 A, which of the following predictions will be wrong?

(a) rNa+/rF- = 0.7

(b) coordination number ofNa+ = coordination number of F " = 6

46. Which of the following is/are examples of banana bond?

(a) A12CI6 (b) A12(CH3)6

47. In which of the following species bond angle is expected to be more than 120°?

(a) PC14+ (b) N O f (c) N02 + (d) XeF2.

48. Which of the following has/have linear shape?

(a) HCN ' (b) (CN)2

49. Which is/are wrong about P4Ol0 molecule?

(a) each P atom can be considered to be sp3 hybridised (b) there are four P - P bonds in the molecule (c) there are two types of P - O bond lengths (d) P O P angle is 180°.

50. Alkenes X and Y on hydration with dilute H2S04

give same alcohol Z. Reductive ozonolysis of X gives P and Q, where only Q gives silver mirror test positively.

Ozonolysis of Y under similar conditions gives only R, which is a dicarbonyl compound and gives positive Tollen's test as well as iodoform test. The product Wof catalytic hydrogenation of X and )' is same which can also be obtained from reduction of all of the following compounds (1 - 5) by Zn-Cu/C,H5OH.

xy ^B, xy & o cr*

(V) (2) (3) (4) (5)

Which ofthe following is/are correct informations about the above reactions?

O (a) R is

(b) X and )' are geometrical isomers

(c) X Br

(d) Z

- a

^OH.

51. Which of the following would be the significant product/s of the given reaction?

H — C = = C - C H - C H ==CH2 H S ( l r a c e S )>

OH I

(a) C H2= C H - C - C H = CH, O

(b) CH2 = CH - CH = CH - CHO (c) H - C = C - C - C H , - C H3

(d) CH, - CH = CH - C = CH OH

52. But-l-ene is formed in reaction/s 0

heat (500°C).

(1) C H , C O , H

N 1 —

| (2) A (heat)

(C)

(d)

53. About oleic acid, the correct statement/s is/are COOH

H H

(oleic acid)

(a) with Br,/CCl4 oleic acid produces a mixture of two optically active stereoisomers

(b) on hydration an optically inactive alcohol derivative is formed (meso isomer)

V -

(iodolactone)

10 CHEMISTRY TODAY | JANUARY '06

(d) one of its reductive ozonolysis product liberates C02 with NaHC03.

54. In which of the following reaction/s alcohol will be formed as the final product?

(a) (CH3CH2CH, -)3B

(b)

CHo — CH — CH,

\ / Hg . +2

(CH3COO")2

H , 0 N a B H , - >

O,, A H,0 (c) CH3 CH = CHMgBr

-V 7 THF (d) CHj - CH2-CH2MgBr ——^ >

55. When neopentyl alcohol is treated with H2S04 a mixture of two alkenes (85 : 15) is formed. Which statement/s is/are correct about these alkenes?

(a) both give same majour product with HBr (b) both give different products (major) with HBr/R202/

light

one obtained in 15% concentration (d) both give same product on ozonolysis.

A N S W E R S

1. (c) 2. (d) 3. (b) 4. (d) 5. (c) 6. (a) 7. (a) 8. (d) 9. (d) 10. (c) 11. (d) 12. (a) 13. (a) 14. (d) 15. (d) 16. (b) 17. (b) 18. (d) 19. (c) 20. (b) 21. (c) 22. (b) 23. (c) 24. (d) 25. (d) 26. (c) 27, (b) 28. (b) 29. (c) 30. (a) 31. (c) 32. (c) 33. (b) 34. (d) 35. (a) 36. (b) 37. (b) 38. (c) 39. (d) 40. (b) 41. (a, b, d) 42. (b, c, d)

43. (a, b, c) 44. (a, b) 45. (d) 46. (b, c) 47. (c, d) 48. (a, b, c, d) 49. (b, d) 50. (a, c, d) 51. (b, d) 52. (a, b, c, d) 53. (a, c, d)

54. (a, b, d) 55. (a, b)

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In document Chemistry Question Bank for Hiighschool (Page 160-163)

Which of the following is correct?