Chemical Sciences Model Paper - MCQ

1.	During the formation of a chemical bond (A) energy decreases (B) energy increases (C) energy of the system does not change (D) electron-electron repulsion becomes more than the nucleus-electron attraction	Answer: (A)
2.	E1, E2 and E3 are the emf values of the three galvanic cells respectively. a) Zn | || |Cu b) Zn | || |Cu c) Zn | || |Cu Which one of the following is true? (A) E3 > E2 > E1 (B) E2 > E3> E1 (C) E1 > E3> E2 (D) E1 > E2> E3	Answer: (A)
3.	Ellingham diagram represents a graph of (A) DG Vs T (B) DG0 Vs T (C) DS Vs P (D) DG Vs P	Answer: (B)
4.	Enthalpy change for the reaction, 4H(g) ® 2H2(g) is –869.6 kJ. The dissociation energy of H – H bond is (A) +217.4 kJ (B) –434.8 kJ (C) –869.6 kJ (D) +434.8 kJ	Answer: (D)
5.	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)
6.	Entropy of the universe is (A) continuously increasing (B) continuously decreasing (C) zero (D) constant	Answer: (A)
7.	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)
8.	Excess of PCl5 reacts with conc. H2SO4 giving (A) chlorosulphonic acid (B) thionyl chloride (C) sulphuryl chloride (D) sulphurous acid	Answer: (C)
9.	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)
10.	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)