Aim IiT 2017 - Class Assignment Mole Concept-2

(1)

1. Element X (Atomic mass = 75) and element Y (Atomic mass = 16) combine to give a compound having 75.8% X. The formula of the compound is –

(a) XY (b) X₂Y (c) X₂Y₂ (d) X₂Y₃

2. The number of moles of oxygen in 1L of air which contains 21% oxygen by volume under standard conditions is –

(a) 0.186mol (b) 0.21mol (c) 2.10mol (d) 0.0093mol

3. How many times an atom of sulpher is heavier than an atom of carbon?

(a) 32 times (b) 12 times (c) 8/3 times (d) 12/32 times

4. The no. of oxygen atoms in 4.4g of CO₂ is approx –

(a) 6×1022 (b) 6×1023 (c) 12×1023 (d) 1.2×1023

5. A sample of CaCO₃ contains 3.01×1023 ions of Ca2+ and CO₃2–. The mass of the sample is –

(a) 100g (b) 50g (c) 200g (d) 5g

6. The empirical formula of a substance which has H,C,O and N in the mass ratio of 1 : 3 : 4 : 7 is –

(a) H₄C₂O₂N₂ (b) H₂CON₂ (c) H₄CON₂ (d) H₄CON

7. What mass of NH₃(g) will be formed when 50kg of N₂(g) and 10.0Kg of H₂(g) are mixed?

(a) 50-23kg (b) 56.66kg (c) 60.7kg (d) 85.0kg

8. How many moles of carbon atoms and hydrogen atoms respectively are present in 3 moles of ethane?

(a) 6, 18 (b) 6, 12 (c) 2, 18 (d) 2, 6

9. Which of the following has largest number of atoms?

(a) 1g Au (b) 1g Na (c) 1gK (d) 1gCl₂

10. Population of a country is approx. 100 million. If one mole of rupees is distributed equally among all the peoples, one person will get rupees approximately ...

(a) 1015 (b) 6.22×1014 (c) 6.022×1015 (d) 10 million

11. A quantity of sulphur has mass 3.2g. What is the mass of calcium having same number of atom?

(a) 0.4g (b) 4g (c) 40g (d) 8g

12. What mass of carbon monoxide has the same number of oxygen atom as are present in 22g CO₂?

(a) 14g (b) 280g (c) 28g (d) 56g

13. Number of atoms of oxygen present in 10.6g of Na₂CO₃ will be –

(a) 6.02×1022 (b) 12.04×1022 (c) 1.806×1023 (d) 31.80×1028

14. For the formation of 3.65g of hydrogen chloride gas, what volumes of hydrogen and chlorine gas are required at N.T.P. conditions?

(a) 1.12L, 1.12L (b) 1.12L, 2.24L (c) 3.65L, 1.83L (d) 1L, 1L

15. An alkaloid contains 17.28% of nitrogen and its molecular mass is 162. The number of nitrogen atoms present in one molecule of alkaloid is –

(a) five (b) four (c) three (d) two

16. ‘X’ grams of calcium carbonate was completely burnt in air. The weight of the solid residue formed is 28g. What is the value of ‘X’ in grams?

(a) 44 (b) 200 (c) 150 (d) 50

17. 20mL of 0.1N BaCl₂ is mixed with 30mL of 0.2N Al₂(SO₄)₃. The mass of BaSO₄ formed is –

(a) 233g (b) 23.3g (c) 2.33g (d) 0.233g

18. 0.224g of a metal when dissolved in dilute acid liberates 275.3cc of hydrogen at 0.ºC and 1 atmosphere pressure. The equivalent mass of the metal is –

(a) 9.216 (b) 0.998 (c) 92.16 (d) 99.8

19. 0.585g of the chloride of a metal dissolved in water and excess of AgNO₃ was added. The mass of precipitated silver chloride after washing and drying was found to be 1.435g. The eq. mass of the metal is –

(2)

20. Same quantity of electricity deposits 0.654g of Zn and 1.0g of another metal. If equivalent mass of Zn is 32.7, then eq. mass of other metal is –

(a) 40 (b) 55 (c) 50 (d) 60

21. A compound of Se and Cl has 52.1% Se. The emprical formula is (At. mass of Se 79.0u)

(a) SeCl (b) SeCl₂ (c) SeCl₃ (d) SeCl₄

22. 3.0 × 1022 atoms of X and 6.0 ×1022 atoms of Y are present in a compound. The empirical formula is –

(a) XY (b) XY₂ (c) XY₃ (d) X₂Y₃

23. Calculate molecular mass of glucose (C₆H₁₂O₆) molecule. Given atomic masses of C, H and O are 12.011 amu, 1.008 amu and 16.00 amu respectively –

(a) 180 amu (b) 180–162 amu (c) 184.32amu (d) 180.262amu

24. 9.6×1017 atoms of irons weight as much 1cm3 of H₂ at STP. What is the atomic mass of iron?

(a) 26 (b) 55.7 (c) 56.0 (d) 58.6

25. The mass of 90% H₂SO₄ that would be required for neutralization of 60g NaOH is –

(a) 0.8167g (b) 81.67g (c) 0.735g (d) 73.5g

26. The no. of electrons present in 18mL water is –

(a) 6.02×1025 (b) 6.02×1023 (c) 6.02×1024 (d) None of these 27. The number of water molecules in 1 litre of water is (N_A represents Avogadro number) –

(a) 18 (b) 18×1000 (c) N_A (d) 55.5N_A

28. The number of atoms present in 0.1mole of P₄ (atomic mass=31) are –

(a) 2.4×104 atoms (b) same as in 0.05 mole of S₈

(c) Same as in 3.2g of sulphur (d) None of these

29. If 3.01×1020 molecules are removed from 98mg of H₂SO₄, then the number of moles of H₂SO₄ left are –

(a) 0.1×10–3 (b) 0.5×10–3 (c) 1.66×10–3 (d) 9.95×10–2

30. A 500 mg iron capsule contains 100mg of ferrous fumarate [(CHCOO)₂Fe]. The percentage of iron present in the capsule is approx –

(a) 6.58 (b) 26.32 (c) 6.43 (d) 13.16

31. If mercury has density of 13.6g cm–3, volume occupied by one atom of mercury (At. Wt. = 200) is – (a) 4.88×10–22 cm3 (b) 2.44×1023cm3 (c) 23

13.6 6.022 10 cm

3 _{(d) 4.88×10}–24_cm3

32. 0.59g of silver salt of an organic acid (molar mass = 210) on ignition gave 0.36g of pure silver. The basicity of the acid is –

(a) 3 (b) 2 (c) 1 (d) 4

33. Which among the following is the heaviest?

(a) one mole of oxygen (b) one mole of sulphur trioxide

(c) 100 amu of uranium (d) 44g of carbon dioxide

34. Find the equivalent mass of zinc if 1.98g of zinc displaced 1.92g of copper from CuSO₄ solution. (equivalent mass of Cu = 31.8) –

(a) 32.79 (b) 32.3 (c) 65.5 (d) 63.5

35. 1.520g of a certain metal hydroxide on ignition gave 0.995g of metal oxide. The equivalent mass of the metal is –

(a) 3 (b) 18 (c) 12 (d) 9

36. One gram of a metalic oxide on reduction gives 0.68g of the metal. The equivalent mass of the metal is –

(a) 68 (b) 34 (c) 51 (d) 17

37. A metal oxide was found to contain 60% of the metal. What is the equialent weight of the metal?

(3)

38. Vapour density of a gas is 40. Its specific heat at constant pressure and volume are 0.115 and 0.082 respectively. The atomic mass of the gas is –

(a) 40 (b) 20 (c) 80 (d) None of these

39. If 0.24g of a volatile liquid upon vapourization gives 45mL of vapours at NTP. What will be the vapour density of the substance? (Density of H₂=0.089gL–1)

(a) 95.39 (b) 5.993 (c) 95.93 (d) 56.0

40. In victor-Meyer’s method, 0.2g of an organic compound displaced 56mL of air at STP. The molecular weight of the compound is –

(a) 56 (b) 112 (c) 80 (d) 28

41. The percentage of Se in peroxidase anhydrous enzyme is 0.5% by weight (atomic weight=78.4). Then minimum molecular weight of peroxidase anhydrous enzyme is –

(a) 1.568×104 (b) 4.568×103 (c) 15.68 (d) 3.136×104

42. The element whose atom has a mass of 6.642×10–26Kg is –

(a) silver (b) zinc (c) calcium (d) boron

43. The weight of 1×1022 molecules of CuSO₄, 5H₂O ix –

(a) 42.42g (b) 41.42g (c) 44.44g (d) 48.94g

44. The number of gram molecules of oxygen in 6.023×1024 CO molecules is –

(a) 10g molecules (b) 5g molecules (c) 1g molecules (d) 0.5g molecules

45. Rearrange the following (I to IV) in the order of increasing masses and choose the correct answer from (1), (2), (3), (4), (Atomic masses : N = 14, O = 16, Cu=63)

(I) 1 molecule of oxygen (II) 1 atom of nitrogen

(III) 1×1010g molecular weight of oxygen (IV) 1×10–18g atomic weight of copper

(a) II < I < IV < III (b) IV < III < II < I (c) II < III < I < IV (d) III < IV < I < II 46. The number of atoms in 4.25g of NH₃ is approximately –

(a) 1×1023 (b) 2×1023 (c) 4×1023 (d) 6×1023

47. 4.4g of an unknown gas occupies 2.24L of volume under N.T.P conditions. The gas may be –

(a) CO₂ (b) CO (c) O₂ (d) SO₂

48. If 1021 molecules are removed from 200mg of CO₂, then the no. of moles of CO₂ left will be –

(a) 2.88×10–3 (b) 1.66×10–3 (c) 4.54×10–3 (d) 1.66×10–2

49. Under similar conditions, oxygen and nitrogen are taken in the same mass. The ratio of their volumes will be –

(a) 7 : 8 (b) 3 : 5 (c) 6 : 5 (d) 9 : 2

50. The number of molecules present in the drop of water (volume = 0.0018 mL) at room temperature is — (a) 6.022 × 1019 (b) 1.084 × 1018 (c) 4.84 × 1017 (d) 6.022 × 1023 51. Which has the maximum number of atoms ?

(a) 6.022 × 1021 molecule of CO₂ (b) 22.4 L of CO₂ at N.T.P

(c) 0.44 g of CO₂ (d) 1 molecule of Ozone

52. The weight of one molecule of compound C₆₀H₁₂₂ is —

(a) 1.2 × 10–20 g (b) 1.4 × 10–21 g (c) 5.025 × 1023 g (d) 6.023 × 1023 g 53. Number of atoms in 635.5 g Cu atomic mass of Cu = 63.55 g mol–1 is —

(a) Twice that in 60 g carbon (b) 6.023 × 1022

(c) Half that of 8 g He (d) 558.6 × 6.023 × 1023 54. The maximum number of molecules are present in —

(a) 5 L of N₂ gas at STP (b) 0.5 g of H₂ gas (c) 10 g of O₂ gas (d) 15 L of H₂ gas at STP 55. Mass of one mole of Protons is —

(4)

56. In a vessel 2 g O₂, 2 g H₂ and 2 g N₂ are present, which has the largest number of atoms ?

(a) O₂ (b) H₂

(c) N₂ (d) All have equal number of atom

57. Assuming that the human body is of 80% water, calculate the no. of molecules that are present in the body of a person who has a mass of 65 kg.

(a) 17.39 × 1025 (b) 17.39 × 1024 (c) 17.39 × 1023 (d) 17.39 × 1026 58. The number of water molecules present in a drop of water weighing 0.018 g is —

(a) 6.022 × 1026 (b) 6.022 × 1023 (c) 6.022 × 1020 (d) 6.022 × 1019 59. 19.7 kg of gold was recovered from a smuggler. How many atoms of gold were recovered ? (Au = 197)

(a) 100 (b) 6.022 × 1023 (c) 6.022 × 1024 (d) 6.022 × 1025 60. The weight of 2.8 L of gas at NTP is 3.50 g its vapour density is —

(a) 14 (b) 25 (c) 32 (d) 20

61. The hydrogen phosphate of certain metal has formula MHPO₄. The formula of metal chloride would be —

(a) MCl (b) MCl₂ (c) M₂Cl2 (d) MCl₃

62. The density of air is 0.001293 g mL–1. Its vapour density is —

(a) 143 (b) 14.3 (c) 1.43 (b) 0.143

63. Phosphine gas (PH₃) on strong heating decomposes into phosphorus [P₄ (S)] and H₂(g). When 100 mL of PH₃(g) at STP is completely decomposed, the change in volume is —

(a) 50 mL (b) –50 mL (c) 200 mL (d) –200 mL

64. Assuming fully decomposed, the volume of CO₂ released at N.T.P on heating 9.85 g of BaCO₃ (Atomic mass of Ba = 137) will be —

(a) 0.84 L (b) 2.24 L (c) 4.06 L (d) 1.12 L

65. The mass of CaCO₃ produced when carbon dioxide is doubled through 500 mL of 0.5 M Ca(OH)₂ solution will be —

(a) 25 g (b) 50 g (c) 20 g (d) 10 g

66. Determine of volume of the product gas when 30 mL of O₂ and 30 mL CO are sparked —

(a) 45 mL (b) 30 mL (c) 15 mL (d) 60 mL

67. The volume in litres of CO₂ liberated at STP when 10 gram of 90% pure limestone is heated completely is —

(a) 22.4 (b) 2.24 (c) 20.16 (d) 2.016

68. An element X has the following isotopic composition 200X : 90%, 199X : 8.0%, 202X : 2.0%. The weighted average atomic mass of the naturally occurring element X is closest to —

(a) 200 amu (b) 199 amu (c) 201 amu (d) 202 amu

69. Hydrogen and nitrogen react to produce ammonia according to the equation : 3H₂

b g

g N₂

b g

g 2NH g₃

b g

What amount of ammonia would be produced if 200 g of hydrogen react ?

(a) 34 g (b) 1.132 kg (c) 11.32 kg (d) 113.2 kg

70. The mass of carbon anode consumed (giving only CO₂) in the production of 270 kg of aluminium metal from bauxite by the Hall’s process is —

(a) 90 kg (b) 180 kg (c) 270 kg (d) 540 kg

71. The amount of zinc needed to produce 112 mL of H₂ at STP on reaction with dil H₂SO₄ will be —

(a) 0.65 g (b) 0.325 g (c) 6.5 g (d) 3.25 g

72. 6.02 × 1020 molecules of sucrose are present in 100 mL of its solution. The number of moles per litre of solution is —

(a) 0.02 (b) 0.01 (c) 0.001 (d) 0.1

73. 5 mL of 1(N) HCl, 20 mL of (N/2) H₂SO₄ and 30 mL of (N/3) HNO₃ are mixed together and the volume made to one litre. The normality of the resulting solution is —

(5)

74. A gas mixture contains 50% helium and 50% methane by volume. The mass percentage of CH₄ in the mixture is—

(a) 19.97% (b) 20.05% (c) 45% (d) 80%

75. During the titration of KMnO₄ with oxalic acid in medium, the oxidation number of Mn7+ changes to —

(a) 0 (b) +2 (c) +3 (d) +5

76. 2 g of aluminium is treated separately with excess of dilute H₂SO₄ and excess of NaOH. The ratio of the volumes of hydrogen evolved is —

(a) 1 : 2 (b) 2 : 1 (c) 1 : 1 (d) 2 : 3

77. An aqueous solution containing 100 grams of dissolved MgSO₄ is fed to a crystallizer where 80% of the dissolved salt crystalises out as MgSO₄ 6H₂O crystals. How many grams of the hexahydrate salt crystals are obtained from the crystallizer ?

(Given atomic masses of Mg = 24, S = 32, O = 16 and H = 1)

(a) 80 (b) 152 (c) 120 (d) 100

78. Oxygen contains 90% 16O and 10% 18O. Its atomic mass is —

(a) 16.2 (b) 17.4 (c) 17 (d) 16.5

79. What is the volume of 0.1 N HCl required to react completely with 1.0 g of pure calcium carbonate ? (Ca = 40, C = 12 and O = 26)

(a) 250 cm3 (b) 150 cm3 (c) 100 cm3 (d) 200 cm3

80. If a mixture containing 3 moles of hydrogen and 1 mole of nitrogen is converted completely into ammonia, the ratio of initial and final volumes at the same temperature and pressure would be —

(a) 1 : 2 (b) 2 : 1 (c) 1 : 3 (d) 3 : 1

81. The molarity of a solution containing 5.6 g of KOH in 250 cm3 solution is —

(a) 0.4 (b) 0.1 (c) 2 (d) 1

82. In the synthesis of ammonia N₂

b g

g 3H₂

b g

g  2NH g₃

b g

.

When 100 mL of N₂ have reacted, the volume of H₂ which has also reacted and ammonia produced are — (a) 300 mL H₂ and 200 mL NH₃ (b) 300 mL H₂ and 300 mL NH₃

(c) 100 mL H₂ and 100 mL NH₃ (d) 100 mL H₂ and 200 mL NH₃

83. 1.5 moles of O₂ combine with Mg to form the oxide MgO. The mass of Mg that has combined is (Mg = 24).

(a) 72 g (b) 36 g (c) 48 g (d) 24 g

84. The volume of water to be added to 100 cm3 of decinormal H₂SO₄ to get centinormal concentration is —

(a) 900 cm3 (b) 500 cm3 (c) 450 cm3 (d) 100 cm3

85. 3 g of an oxide of a metal is converted to chloride completely and it yielded 5 g of chloride. The equivalent weight of metal is —

(a) 33.25 (b) 3.325 (c) 12 (d) 20

86. 30 g of magnesium and 30 g of oxygen are reacted and the residual mixture contains.

(a) 60 g of magnesium oxide only (b) 40 g of magnesium oxide and 20 g of oxygen (c) 45 g of magnesium oxide and 15 g of oxygen (d) 50 g of magnesium oxide and 10 g of oxygen

87. On heating a given mass of blue vitriol 95.7 g anhydrous copper sulphate is obtained. The number of water molecules lost are —

(a) 3 (b) 18.06 × 1023 (c) 5 (d) 30.10 × 1023

88. The equivalent weight of a certain trivalent element is 20. Molecular weight of its oxide is —

(a) 168 (b) 68 (c) 152 (d) 56

89. The percentage of silver in lunar caustic is —

(6)

90. A wedding ring presented to a bride contains 788 mg of gold and the rest is diamond. If the ring weighs 1g, the bride receives (At. mass of Au = 197, C = 12)

(a) More number of gold atoms (b) More number of carbon atoms

(c) Equal number of gold and carbon atoms (d) Gold and carbon atoms in ratio of 4 : 1 approximately 91. 13.5 g of aluminium when changes to Al3+ ion in solution, will lose —

(a) 18.0 × 1023 electrons (b) 6.022 × 1023 electrons (c) 3.01 × 1023 electrons (d) 9.1 × 1023 electrons 92. To prepare a solution of concentration of 0.03 g/mL of AgNO₃, what amount of AgNO₃ should be added in 60

mL of solution ?

(a) 0.8 g (b) 1.8 g (c) 0.18 g (d) None of these

93. A purified cytochrome protein was found to contain 0.376% iron. What is the minimum molecular mass of the protein ?

(a) 14, 800 u (b) 1480 u (c) 148,000 u (d) 148 u

94. A mixture containing 100 g H₂ and 100 g O₂ is ignited so that water is formed according to the reaction, 2H₂O₂2H O₂ ; how much water will be formed ?

(a) 50 g (b) 100 g (c) 175 g (d) 113 g

95. In a compound C, H and N are present in the ratio 9 : 1 : 3.5 by weight. Molecular mass of the compound is 108. Molecular formula of the compound is —

(a) C₂H₆N₂ (b) C₃H₄N (c) C₆H₈N₂ (d) C₉H₁₂N₃

96. What volume of hydrogen gas at 273 K and 1 atm pressure will be consumed in obtaining 21.6 g elemental boron (atomic mass = 10.8) from the reduction of boron trichloride by hydrogen ?

(a) 67.2 L (b) 44.8 L (c) 22.4 L (d) 89. 6L

97. One mole of magnesium nitride on reaction with an excess of water gives — (a) One mole of ammonia (b) Two mole of nitric acid (c) Two moles of ammonia (b) One mole of nitric acid

98. How many moles of magnesium phosphate, Mg₃

b

PO_{4 2}

g

will contain 0.25 mole of oxygen atoms ? (a) 3.125 × 10–2 (b) 1.25 × 10–2 (c) 2.5 × 10–2 (d) 0.02

99. In the reaction 2Al(s) + 6HCl (aq)  2Al3+(aq) + 6Cl–(aq) + 3H₂(g)

(a) 33.6 L H₂ (g) is produced regardless of temperature and pressure for every mole of Al that reacts (b) 67.2 L H₂ (g) at STP is produced for every mole of Al that reacts

(c) 11.2 L H₂(g) at STP is produced for every mole HCl (aq) consumed (d) 6 L HCl (aq) is consumed for every 32 H₂(g) is produced

100. The total number of valence electrons in 4.2 g of nitride ion (N3–) are —

(a) 3 N_A (b) 4.2 N_A (c) 3.2 N_A (d) 1.6 N_A

101. How many moles of electrons weigh one kilogram ?

(Mass of electron = 9.108 × 10–31 kg, Avogadro number = 6.022 × 1023) (a) 6.022 × 1023 (b) 1 1031 9.108 (c) 54 6.022 10 9.108 (d) 8 1 10 9.108 6.022  102. Which has maximum number of atoms ?

(a) 24 g of C (12) (b) 56 g of Fe (56) (c) 27 g of Al (27) (d) 108 g of Ag (108) 103. How many grams of CaO are required to neutralize 852 g of P₄O₁₀ ?

(a) 958 g (b) 1008 g (c) 1032 g (d) 993.9 g

104. 0.0833 mol of carbohydrate of empirical formula CH₂O contain 1 g of hydrogen. The molecular formula of the carbohydrate is —

(7)

105. How many H-atoms are present in 0.046 g of ethanol ?

(a) 6 × 1020 (b) 1 : 2 × 1021 (c) 3 × 1021 (d) 3.6 × 1021 106. Which element exist as a solid at 25ºC and 1 atmospheric pressure among the following ?

(a) Br (b) Cl (c) Hg (d) P

107. For the reaction Na CO₂ ₃2HCl2NaClH O₂ CO₂ Equivalent weight of Na₂CO₃ is —

(a) M/2 (b) M (c) 2M (d) M/4

108. The mass of 112 cm3 of CH₄ gas at STP is —

(a) 0.16 g (b) 0.8 g (c) 0.08 g (d) 1.6 g

109. A hydrocarbon contains 10·5 g Carbon and 1 g hydrogen. Its 0.36 g has 1 L volume at 1 atm and 127ºC, the hydrocarbon is —

(a) C₆H₇ (b) C₇H₈ (c) C₅H₆ (d) None of these

110. A compound contains 54.55% carbon 9.09% hydrogen, 36.36% oxygen. The empirical formula of this compound is —

(a) C₃H₅O (b) C₄H₈O₂ (c) C₂H₄O₂ (d) C₂H₄O 111. Equivalent weight of an acid —

(a) Depends on the reaction involved (b) Depends upon the number of oxygen atoms present (c) Is always constant (d) None of the above

112. How many moles of Al₂(SO₄)₃ would be present in 50 g of the substance ?

(a) 0.083 mole (b) 0.952 mole (c) 00481 mole (d) 0.140 mole

113. One mole of CO₂ contains —

(a) 3 g atoms of CO₂ (b) 18.1 × 1023 molecules of CO₂ (c) 6.02 × 1023 atoms of O (d) 6.02 × 1023 atoms of C 114. The mass of 1 mole of electrons is —

(a) 9.1 × 10–28 g (b) 1.008 mg (c) 0.55 mg (d) 9.1 × 10–27 mg 115. 0.56 g of gas occupies 280 cm3 at NTP, then its molecular mass is —

Aim IiT 2017 - Class Assignment Mole Concept-2

b g

b g

b g

b g

b g

b g

b

g

1. (d)

2. (d)

3. (c)

4. (d)

5. (b)

6. (c)

7. (b)

8. (a)

9. (b)

10. (c)

11. (b)

12. (c)

13. (c)

14. (a)

15. (d)

16. (d)

17. (d)

18. (a)

19. (a)

20. (c)

21. (b)

22. (b)

23. (b)

24. (c)

25. (b)

26. (c)

27. (d)

28. (c)

29. (b)

30. (a)

31. (b)

32. (a)

33. (b)

34. (a)

35. (d)

36. (d)

37. (b)

38. (a)

39. (d)

40. (c)

41. (a)

42. (c)

43. (b)

44. (a)

45. (a)

46. (d)

47. (a)

48. (a)

49. (a)

50. (a)

51. (b)

52. (b)

53. (a)

54. (d)

55. (c)

56. (b)

57. (d)

58. (c)

59. (d)

60. (a)

61. (b)

62. (b)

63. (a)

64. (d)

65. (a)

66. (a)

67. (d)

68. (a)

69. (b)

70. (a)

71. (b)