PAPER – I

 

61. A radioactive isotope having a half-life of 3 days was received after 12 days. It was found that there were 3g of the isotope in the container. The initial weight of the isotope when packed was

(A) 12g                                                            (B) 24g

(C) 36g                                                            (D) 48g

 

62. Which one has peroxide linkage?

(A)                                                        (B)

(C)                                                        (D)

 

63. Among the following compounds the one that is polar and has the central atom with sp³ hybridisation is

(A) H₂CO₃                                                       (B) SiF₄

(C) BF₃                                                            (D) HClO₂

 

64. A solution contains Na₂CO₃ and NaHCO₃. 10 ml of the solution required 2.5 ml of 0.1 M H₂SO₄ for neutralisation using phenolphthalein as indicator. Methyl orange is then added when a further 2.5 ml of 0.2 M H₂SO₄ was required. The amount of Na₂CO₃ and NaHCO₃ in 1 litre of the solution is

(A) 5.3 g and 4.2 g                                          (B) 3.3 g and 6.2 g

(C) 4.2 g and 5.3 g                                          (D) 6.2 g and 3.3 g

 

65. The values of observed and calculated molecular weights of silver nitrate are 92.64 and 170 respectively. The degree of dissociation of silver nitrate is

(A) 60%                                                           (B) 83.5%

(C) 46.7%                                                        (D) 60.23%

 

66. 10 ml of a strong acid solution of pH = 2 are mixed with 990 ml of another strong acid solution of pH = 4. The pH of the resulting solution will be:

(A) 4.002                                                         (B) 4.8

(C) 4.2                                                             (D) 3.72

 

67. The pH of pure water at 25°C and 35°C are 7 and 6 respectively. The heat of formation of water from H⁺ and OH^– are

(A) 84.55 kcal mol^–1                                       (B) – 84.55 kcal mole^–1

(C) 74.55 kcal mol^–1                                       (D) – 74.55 kcal mole^–1

 

66. Which reaction is endothermic in nature?

(A) Fe + S ¾® FeS                                       (B) NaOH + HCl ¾® NaCl + H₂O

(C) CaCO₃ ¾® CaO + CO₂                         (D) CH₄ + 2O₂ ¾® CO₂ + 2H_­2O

 

69. In a face centred cubic arrangement of A and B atoms whose A atoms are at the corner of the unit cell and B atoms are at the face centres. One of the A atom is missing from one corner in unit cell. The simplest formula of the compound is:

(A) A₇B₃                                                          (B) AB₃

(C) A₇B₂₄                                                         (D) A_7/8B₃

 

70. Which pair of elements is chemically most similar?

(A) Na, Al                                                        (B) Cu, S

(C) Ti, Zr                                                          (D) Zr, Hf

 

71. An inorganic compound first melts then resolidifes and then liberates a gas. It may be:

(A) KClO₃                                                        (B) KMnO₄

(C) Al₂O₃                                                         (D) BeCl₂

72. Which is maximum hydrated

(A) NaCl                                                          (B) MgCl_­2

(C) AlCl₃                                                          (D) BeCl_­2

 

73. Between p-nitrophenol and salicyaldehyde, solubility in base is

(A) Almost nil in both cases                            (B) Higher in p-nitrophenol

(C) Higher for salicylaldehyde                        (D) Equal in nature

 

74. An organic compound C­₃H₆O does not give a precipitate with 2, 4-dinitrophenylhydrazine reagent and does not react with sodium metal. It could be

(A) CH₃ – CH₂ – CHO                                    (B) CH₃ – COCH₃

(C) CH₂ = CH – CH₂OH                                 (D) CH₂ = CH – OCH₃

 

75. The reagent which can be used to distinguish acetophenone from Benzophenone is:

(A) 2, 4-dinitrophenylhydrazine                       (B) aqueous NaHSO₃

(C) Benedict’s solution                                    (D) I­₂ and NaOH

 

76. The bond length is O₂⁺, O₂, O₂^– and O₂^2– follows the order

(A) O₂^2– > O₂^– > O₂ > O₂⁺                              (B) O₂⁺ > O₂ > O₂^– > O₂^2–

(C) O₂ > O₂^– > O₂^2– > O₂⁺                              (D) O₂^– > O₂^2– > O₂⁺ > O₂

 

77. CuSO₄ solution reacts with KCN to form a complex

(A) Cu(CN)₂                                                    (B) Cu(CN)

(C) K₂[Cu(CN)₄]                                              (D) K₃[Cu(CN)₄]

 

78. The first ionisation potential of aluminium is less than that of magnesium, because

(A) atomic size of Al < Mg                              (B) Atomic size of Al > Mg

(C)  Al has one electron in p-orbital                (D) none

 

79. Solubility of alkaline earth metal hydroxides increases from, Be(OH)₂ to Ba(OH)₂ because

(A) Lattice energy > Hydration energy

(B) Hydration energy > Lattice energy

(C)  Lattice energy is equal to hydration energy

(D) none of these

 

80. Which statement is correct with respect to the property of the elements with increase in atomic number in the carbon family.

(A) Their metallic character decreases          (B) The stability of +2 oxidation state increases

(C)  Their ionisation energy increases            (D) Their atomic size decreases

 

81. The magnetic behaviour of complexes K₄[Fe(CN)₆] and K₃[Fe(CN)₆].

(A) Diamagnetic , ferromagnetic                    (B) Paramagnetic, diamagnetic

(C)  Diamagentic, paramagnetic                    (D) none of these

 

82. Which of the interhalogen compound does not exist?

(A) BrF₅                                                           (B) ClF₃

(C)  FCl₃                                                          (D) ClF

 

83.
(A)			(B)
(C)			(D)

 

84.
(A)			(B)
(C)			(D)

 

85.
(A)			(B)
(C)			(D)	None of these

 

86.
(A)			(B)
(C)			(D)

 

87. p-benzoquinone reacts with excess 1, 3-butadiene. The product is

(A)		(B)
(C)		(D)	None

 

88. A Nitration product. The rate will be maximum, when A is

(A)		(B)
(C)		(D)

 

89. CO(OEt)₂ ultimate product would be

(A) Ketone                                                       (B) Aldehyde

(C) Tertiary alcohol                                         (D) None

 

90. Which of the following compound doesn’t undergo decarboxylation on heating?

(A)		(B)
(C)		(D)

 

Answers

 

61. D                                         

.                 62.       A                                          63.       D                                          64.       A        

65. B                                          66.       D                                          67.       B        
66. 68. C                                                 C                                          70.       D        
67. A                                          72.       D                                          73.       B        
68. D                                          75.       D                                          76.       A        
69. D                                          78.       C                                          79.       B        
70. B                                          81.       C                                          82.       C        
71. 83. A                                          84.       A                                                 B        
72. D                                          87.       D                                          88.       D        
73. C                                          90.       B

 

Hints & Solutions

 

61. n = = 4

\ N₀ = N ´ 2ⁿ = 3 ´ 2⁴ = 48g

 

62.

 

63. Carbon in H₂CO₃ has sp² hybridsation and non-polar. BF₃has sp² hybridisation but non-polar. SiF₄ and HClO₂ has sp³hybridisation but HClO₂ is polar.

 

64. For phenolphthalein

Meq. of Na₂CO₃ = 2.5  ´ 0.1 ´ 2 = 0.5

For methyl orange

Meq. of Na₂CO₃ + Meq. of NaHCO₃ = 2.5 ´ 0.2 ´ 2 = 1.0

\ Meq. of NaHCO₃ = 0.5 and Meq. of Na­₂CO₃ = 1.0

= 0.5 1000 = 1

W = 0.042 g in 10 mL \ W = 0.053 g in 10 mL

\ W = 4.2 g in 1 litre = 5.3 g in 1 litre

 

65. i for AgNO₃ = = 1 + a

a =  – 1 = 0.835 = 83.5%

 

66. [H⁺] after mixing = = 1.9 ´ 10^–4

pH = 3.72

 

67. At 25°C [H⁺] = 10^–7; \ K_w = 10^–14

At 35°C [H⁺] = 10^–6; \ K_w = 10^–12

Now using,

2.303 log

We get, DH = 84.55 kcal/mole

Thus H₂O  H⁺ + OH^–                              DH = 84.55

\ H⁺ + OH^–  H₂O                                   DH = – 84.55 kcal/mole

 

68. Decomposition of CaCO₃ is made on heating.

 

69. No. of atoms of A from corners of unit cell =

No. of atoms of B from faces of unit cell = 3

Thus A : B : : 3 (or) 7 : 24

 

70. Due to Lanthanide contraction.

 

72. Smaller is the ion, more is the hydration

 

73. Because of acidic nature

 

74. It is neither a carbonyl compound (do not give a test with hydrazine) nor an alcohol and thus it may be ether.

 

75. Acetophenone will show iodoform Test

                                                                                         

76. The bond length decreases with increase in bond order in diatomic molecule A result of molecular orbital theory.

 

78. Removal of electron from 2p shell is easier in comparison to 2s shell

 

80. Due to inert pair effect which increases down the group

 

81. K₄[Fe(CN)₆] ® Fe²⁺, d⁶ – configuration

CN^– strong ligand

¾®

Diamagnetic

K₃[Fe(CN)₆] ¾® Fe³⁺, d⁵ configuration

 

¾®

Paramagnetic

 

84.

 

85. In Baeyer-Villiger oxidation, group having higher migratory aptitude migrates on oxygen.

 

87.

 

90. Double bond at bridge head position is not possible due to strain.