For a stable molecule the value of bond order must be positive

193.    Enthalpy of vapourization of benzene is +35.3 kJ mol-1 at its boiling point of 80°C.The entropy change in the transition of the vapour to liquid at its boiling point

[in JK-1 mol-1] is ______.

(A) -100

(B) -441

(C) +100

(D) +441

Answer:: (A)

194.    Entropy of the universe is

(A) continuously increasing

(B) continuously decreasing

(C) zero

(D) constant

Answer:: (A)

195.    Excess of carbon dioxide is passed through 50 ml of 0.5 M calcium hydroxide solution.  After the completion of the reaction, the solution was evaporated to dryness. The solid calcium carbonate was completely neutralised with 0.1 N Hydrochloric acid. The volume of Hydrochloric acid required is (At. mass of calcium = 40)

(A) 500 cm3

(B) 400 cm3

(C) 300 cm3

(D) 200 cm3

Answer:: (A)

196.    Excess of PCl5 reacts with conc. H2SO4 giving

(A) chlorosulphonic acid

(B) thionyl chloride

(C) sulphuryl chloride

(D) sulphurous acid

Answer:: (C)

197.    For a chemical reaction A ® B, the rate of the reaction is 2 ´ 10-3 mol dm-3 s-1, when the initial concentration is 0.05 mol dm-3. The rate of the same reaction is 1.6 ´ 10-2 mol dm-3 s-1when the initial concentration is 0.1 mol dm-3. The order of the reaction is

(A) 3

(B) 1

(C) 2

(D) 0

Answer:: (A)

198.    For a stable molecule the value of bond order must be

(A) negative

(B) positive

(C) zero

(D) there is no relationship between stability and bond order.

Answer:: (B)

200.    For alkali metals, which one of the following trends is INCORRECT?

(A) Ionization energy: Li > Na > K > Rb

(B) Hydration energy: Li > Na > K > Rb

(C) Atomic size: Li < Na < K < Rb

(D) Density: Li < Na < K < Rb

Answer:: (D)