PAPER – IV

 

 

61. Photoelectric emission is observed from a surface for frequencies n₁ and n₂ of the incident radiation (n₁ > n₂). If the maximum kinetic energies of the photoelectrons in the two cases are in the ratio 1 : k then the threshold frequency n_o is given by

(A)                                       (B)

(C)                                                    (D)

 

62. Energy levels A, B, C of a certain atom corresponds to increasing values of energy i.e.
    E_A < E_B < E_C. If l₁, l­₂ and l₃ are the wavelengths of radiations corresponding to the transitions C to B, B to A and C to A respectively, which of the following statement is correct.

 

(A) l₃ = l₁ + l₂                                               (B) l₃ =

(C) l₁ + l_­2 + l₃ = 0                                         (D) l₃² = l₁² + l₂²

 

63. Three isotopes of an element have mass numbers, M, (M+1) and (M+2). If the mean mass number is (M + 0.5) then which of the following ratios may be accepted for M, (M + 1),
    (M + 2) in that order

(A) 1 : 1 : 1                                                      (B) 4 : 1 : 1

(C) 3 : 2 : 1                                                      (D) 2 : 1 : 1.

 

64. When photons of energy 4.25 eV strike the surface of a metal A, the ejected photoelectrons have maximum kinetic energy, T_A (expressed in eV) and de Broglie wavelength l_A. The maximum kinetic energy of photoelectrons liberated from another metal B by photons of energy 4.20 V is T_B = T_A – 1.50 eV. If the de-Broglie wavelength of these photoelectrons is
    l_B = 2l_A, then

(A) the work function of A is 2.25 eV             (B) the work function of B is 4.20 eV

(C) T_A = 2.00 eV                                             (D) T_B = 2.75 eV.

 

65. 0.7 g of a sample of Na₂CO₃×xH₂O were dissolved in water and the volume was made to 100 ml, 20 ml of this solution required 19.8 ml of N/10 HCl for complete neutralization. The value of x is

(A) 7                                                                (B) 3

(C) 2                                                                (D) 5

 

66. Which graph correctly correlates E_cell as a function of concentrations for the cell (for different values of M and M¢)

Zn(s) + Cu⁺² (M) ¾® Zn²⁺(M¢) + CuS; E⁰_cell = 1.10 V

X axis: log₁₀ , Y axis; E_cell

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

 

67. A hydrogen electrode placed in a buffer solution of CH₃COONa and acetic acid in the ratio’s x:y and y:x has electrode potential values E₁ volts and E₂ volts respectively at 25^oC. The pK_a values of acetic acid is (E₁ & E₂ are oxidation potential).

(A)                                                    (B) 0

(C)                                                (D)0

 

68. A 0.518 g sample of limestone is dissolved in HCl and then the calcium is precipitated as CaC₂O₄. After filtering and washing the precipitate, it requires 40.0 mL of 0.250 N KMnO₄, solution acidified with H₂SO₄ titrate as, MnO₄^– + H⁺ + C₂O₄^2– ¾® Mn²⁺ + CO₂ + 2H₂O. The percentage of CaO in the sample is

(A) 54.0%                                                        (B) 27.1%

(C) 42%                                                           (D) 84%

 

69. An element A in a compound ABD has oxidation number A^n–. It is oxidised by Cr₂O₇^2– in acid medium. In the experiment 1.68 ´ 10^–3 moles of K₂Cr₂O₇ were used for 3.26 ´ 10^–3 moles of ABD. The new oxidation number of A after oxidation is.

(A) 3                                                                (B) 3 – n

(C) n – 3                                                          (D) + n

 

70. At 40^oC the vapour pressures in torr, of methyl alcohol – ethyl alcohol solutions is represented by the equation. P = 119X_A + 135 where X_A is mole-fraction of methyl alcohol, then the value of is

(A) 254 torr                                                      (B) 135 torr

(C) 119 torr                                                     (D) 140 torr

 

71. A substance undergoes first order decomposition. The decomposition follows two parallel first order reactions as:

 

The percentage distribution of B and C are:

(A) 80% B and 20% C                                          (B) 76.83% B and 23.17% C.

(C) 90% B and 10% C                                          (D) 60% B and 40% C

 

72. Calculate the molal elevation constant of water which evaporates at 100°C with absorption of 536 cal/gm

(A) 0.519°                                                        (B) 0.612°

(C) 0.915°                                                       (D) 0.621°

 

73. A radioactive isotopes decays at such a rate that after 96 minutes only 1/8th of the original amount remains. The t_1/2 of the nuclei is

(A) 12 minutes                                                (B) 32 minutes

(C) 24 minutes                                                (D) 48 minutes

 

74. The root mean square velocity of an ideal gas is given by the expression

 

When the pressure is doubled at constant temperature

(A) U_r.m.s. increases Ö2 times                          (B) U_r.m.s. is doubled

(C) U_r.m.s. remains unchanged                        (D) U_r.m.s. increases by three times

 

 

75. The shape of [Cu(NH₃)₄]²⁺ is square planar, Cu²⁺ in this complex is

(A) sp³ hybridised                                           (B) dsp² hybridised

(C) sp³d hybridised                                         (D) sp³ d² hybridised

 

76. Prussian blue is formed when

(A) ferrous sulphate reacts with FeCl₃

(B) ferric sulphate reacts with K₄[Fe(CN)₆]

(C) ferrous ammonium sulphate reacts with FeCl₃

(D) ammonium sulphate reacts with FeCl₃

 

77. Concentrated NaOH can separate a mixture of

(A) Al³⁺ and Cr³⁺                                             (B) Cr³⁺ and Fe³⁺

(C) Al³⁺ and Zn²⁺                                             (D) Zn²⁺ and Pb²⁺

 

78. The hybridisation of boron in orthoboric acid is

(A) sp³                                                             (B) sp²

(C) sp                                                              (D) sp³d

 

79. In concentrated sodium thiosulfate solution silver nitrate gives

(A) white ppt of Ag₂S₂O₃                                (B) soluble complex of Na₃[Ag(S₂O₃)₂]

(C) Black ppt of Ag₂S                                     (D) black ppt of Ag.

 

80. Which complex is diamagnetic

(A) [Fe(CN)₆]^4–                                               (B) [Cu(NH₃)₄]²⁺

(C) [Ti(H₂O)₆]³⁺                                               (D) None

 

81. Which of the following pairs of isomers and types of isomerism are correctly matched
82. [Co(NH₃)₅(NO₂)]Cl₂ and [Co(NH₃)₅(ONO)]Cl₂ ……..linkage
83. [Cu(NH₃)₄] [PtCl₄] and [Pt(NH₃)₄][CuCl₄] —— Coordination
84. [Pt(NH₃)₄Cl₂]Br₂ and [Pt(NH₃)₄Br₂]Cl₂.. Ionization

(A) 2 and 3                                                      (B) 1,2 and 3

(C)  1 and 3                                                     (D) 1 and 2

 

82. 3, 5-dimethylcyclopentene Identify major product.

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

 

83. CH₂ = CH – CN Z is major product. So Z is

(A)		(B)
(C)		(D)	EtO – CH2 – CH2 – CN

 

84. Which of the following compound is optically active?

(A)	CH2 = C = CH – Me	(B)
(C)		(D)

 

85.
(A)			(B)
(C)			(D)

 

86. PhCHO + MeCHO

(A) Ph – CH = CH – CH₂OH                          (B) Ph – CH₂CH₂ – CH₂OH

(C) Ph – CH₂ – CH₂ –– OH                        (D) None

 

 

87.
(A)			(B)
(C)			(D)

 

88. Cyclooctatetraene is not aromatic. The reason for this is that

(A) It has eight p electrons

(B) It is a planar molecule

(C) Its structure is not that of a regular octagon

(D) Its structure can not be described by more than two canonical forms

 

89. Which of the following compounds can be optically active

(A)		(B)
(C)	CH2 = CH – CH3	(D)

 

90. Consider the following pairs of compounds

a)
b)

of these pairs

(A) Both a and b are resonance forms

(B) both a and b are tautomeric forms

(C) A is a resonance pair while B is a pair of tautomers

(D) A is a pair of tautomers while B is a resonance pair

Answers

61. B                                         

.                 62.       B                                          63.       B                                                      64.       D        

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