March 08, 2012

Chemical Kinetics - II One Mark Questions

1. 50% of a first order reaction is completed in 20 minutes. The time required for 75% completion is
a) 60 minutes         b) 10 minutes              c) 40 minutes               d) 80 minutes.
2. Decomposition of nitrogen pentoxide in CCl4 is an example for
a) second order reaction                            b) third order reaction
c) zero order reaction                                d) first order reaction.
3. For a reaction Ea = 0 and k = 4.2 x 105 sec–1 at 300 K, the value of k at 310 K will be
a) 4.2 x 105 sec–1                                       b) 8.4 x 105 sec–1
c) 8.4 x 10-5 sec–1                                       d) 4.2 x 10-5 sec–1 / unpredictable.
4. For a reaction: aA → bB, the rate of reaction is doubled when the concentration of A is increased by four times. The rate of reaction is equal to
a) k [A]a                 b) k [A]½                     c) k [A]1/a                     d) k [A]
5. Half-life period of a first order reaction is 20 min. The time taken for the completion of 99.9% of the reaction is
a) 20 min               b) 2000 min                 c) 250 sec                    d) 200 min.
6. Hydrolysis of an ester by dilute HCl is an example for
a) zero order reaction                                b) first order reaction
c) second order reaction                            d) pseudo first order reaction.
7. If the activation energy is high then the rate of the reaction is
a) high                   b) moderate                 c) low                             d) cannot be predicted.
8. In a first order reaction the concentration of the reactant is increased by 2 times. The rate of the reaction is increased by
a) 2 times               b) 4 times                    c) 10 times                   d) 6 times.
9. Reactions in which the reacting molecules react in more than one way yielding different set of products are called
a) consecutive reactions                            b) parallel reactions
c) opposing reactions                                d) chain reactions
10. The excess energy which a molecule possesses to become active is known as
a) kinetic energy                                        b) potential energy
c) activation energy                                   d) threshold energy.
11. The first order rate constant of a reaction is 0.0693 min–1. Then the time required for 50% completion of a reaction is
a) 10 min               b) 1 min                       c) 100 min                   d) 50 min.
12. The half-life period of a first order reaction is 10 minutes. The rate constant is
a) 6.93 x 102 min–1                                    b) 0.693 x 10–2min
c) 6.932 x 10–2 min–1                                 d) 69.3 x 10–1 min–1
13. The sum of the powers of the concentration terms that occur in the rate equation is called
a) molecularity      b) order                       c) rate                          d) rate constant.
14.  The t1/2 of a first order reaction is 100 minutes. The rate constant of the reaction is
a) 6.93 x 103 min–1                                    b) 0.693 x 10–1 min–1
c) 6.93 x 10-3 min                                      d) 69.3 x 10–2 min
15. The unit of zero order rate constant is
a) sec–1                                                       b) mol lit–1 sec–1
c) mol sec–1                                                d) lit2 sec–1.
16. Arrheniusequation is
a) k = Ae–1/RT         b) k = Ae–RT/Ea         c) k = Ae–Ea/RT        d) k = AeEa/RT