Chemistry: Section - A (Q. No. 51 to 85)
54. On heating, some solid substances change from solid to vapour state without passing through liquid state. The technique used for the pruification of such solid substances based on the above principle is known as
(1) Distillation
(2) Chromatography
(3) Crystallization
(4) Sublimation
57. The highest number of helium atoms is in
(1) 4 g of helium
(2) 2.271098 L of helium at STP
(3) 4 mol of helium
(4) 4 u of helium
58. For the reaction 2 A ⇌ B + C, `K_c = 4 \times 10^{-3}`. At a given time, the composition of reaction mixture is :
[A] = [B] = [C] = `2 \times 10^{-3} M`
Then, which of the following is correct?
(1) Reaction has a tendency to go in backward direction.
(2) Reaction has gone to completion in forward direction.
(3) Reaction is at equilibrium.
(4) Reaction has a tendency to go in forward direction.
60. Fehling's solution 'A' is
(1) alkaline solution of sodium potassium tartrate (Rochelle's salt)
(2) Aqueous sodium citrate
(3) aqueous copper sulphate
(4) alkaline copper sulphate
65. Arrange the following elements in increasing order of electronegativity:
N, O, F, C, Si
Choose the correct answer from the options given below:
(1) O < F < N < C < Si
(2) F < O < N < C < Si
(3) Si < C < N < O < F
(4) Si < C < O < N < f
75. The Henry's law constant `(K_H)` values of three gases (A, B, C ) in water are 145, `2 \times 10^{-5}` and 35 kbar, respectively. The solubility of these gases in water follow the order :
(1) A > C > B
(2) A > B > C
(3) B > A > C
(4) B > C > A
78. The energy of an electron in the ground state (n = 1) for `He^+` ion is -x J, then that for an electron in n = 2 state for `Be^{3+}` ion in J is :
(1) `- 4 x`
(2) `- \frac{4}{3} x`
(3) `- x`
(4) `- \frac{x}{9}`
79. A compound with a molecular formula of `C_6 H_{14}` has two tertiary carbons. Its IUPAC name is :
(1) 2,3 - dimethylbutane
(2) 2,2 - dimethylbutane
(3) n - hexane
(4) 2 - methylpentane
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