NCERT Class 12 Chemistry Multiple Choice Questions(MCQs) & Answers
23 Physical adsorption of a gaseous species may change to chemical adsorption with ___________ .
Answer: increase in temperature
24 When Cl2 reacts with hot and cone. NaOH, the oxidation number of chlorine changes from
Answer: 0 to -1 and 0 to +5
25 The emf of the cell: Ni / Ni2+ (1.0 M) // Au3+ (1.0 M) / Au (E° = -0.25 V for Ni2+/Ni; E° = 1.5 V for Au3+/Au) is
Answer: 1.75 V
26 The half life period of first order reaction is 1386 seconds. The specific rate constant of the reaction is
Answer: 0.5 × 10-3 s-1
27 The rate constant of a reaction A → B is 0.6 × 103 mole per second. If the concentration of [A] is 5 M, then what will be concentration of [B] after 20 months?
Answer: 0.72 M
28 Fluorine differs from rest of the halogens in some of its properties. This is due to
Answer: lack of d-orbitals.
30 Extraction of gold and silver involves leaching with CN–. Silver is later recovered by
Answer: Displacement by Zn