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31) The half-life for the decomposition of N2O5 is 1,
117.75. What is the first order rate constant for this decomposition?
a) 6.2 x 10-2s-1
b) 6.5 x 10-4s-1
c) 6.5 x 10-2s-1
d) 6.2 x 10-4s-1
ANSWER : 6.2 x 10-4s-1
32) If the activation energy of a reaction is zero, then the rate constant
(K) of the reaction:
a) Decreases with the decrease in temperature.
b) Is nearly independent of temperature.
c) Increases with the increase in temperature.
d) Decreases with the decrease in temperature.
ANSWER : Is nearly independent of temperature.
33) The half-life period for a reaction is 0.693. What will be the time
required for the completion of 99% of a first order reaction?
a) 2 x 2.303 days.
b) 2.303 x 0.693 days.
c) 2 x 0.693 days. d) 2.303 x 3 days.
ANSWER : 2 x 2.303 days.
34) What is the value of energy of activation for the reaction if the heat
of a reaction is 20 kcal?
a) < 20 kcal.
b) =20 kcal.
c) >20 kcal.
d) Cannot be predicted.
ANSWER : >20 kcal.
35) In an endothermic reaction ?H represents the enthalpy of the reaction in
kJ / mol. What is the minimum value for the energy of activation?
a) Zero
b) More than ?H
c) Less than ?H
d) Equal to ?H
ANSWER : More than ?H
36) What is the rate of change of concentration of ammonia if the rate of
change of concentration for hydrogen is -0.3 x 10-4 Ms-1.
The reaction is N2 + 3H2 ? 2 NH3.
a) + 0.2 x 10-4 Ms-1
b) -0.3 x 10-4 Ms-1
c) +0.3 x 10-4 Ms-1
d) -0.2 x 10-4 Ms-1
ANSWER : + 0.2 x 10-4 Ms-1
37) In an exothermic reaction, if Ef and Er are the activation energies of
forward and reverse reactions, then:
a) Ef = Er
b) Ef < Er
c) Ef > Er
d) No relation can be given between Ef and Er as data are not sufficient.
ANSWER : Ef < Er
38) In a photochemical reactions:
a) The temperature has opposite effect as on thermal reactions.
b) Temperature has no effect.
c) Temperature may have little in certain cases.
d) The temperature has the same effect as on thermal reactions.
ANSWER : Temperature has no effect.
39) The number of atoms or molecules whose concentration alters during a
chemical change is its:
a) Molecularity.
b) Molarity.
c) Order of reaction.
d) Change in reaction.
ANSWER : Order of reaction.
40) Find the rate of consumption of H2, if the rate of formation
of ammonia is 34gm hour-1. The reaction is N2 + 3H2
? 2 NH3.
a) 8/3 gm hour-1
b) 6 gm hour-1
c) 4/3 gm hour-1
d) 12 gm hour-1
ANSWER : 6 gm hour-1
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Part 5
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