Sunday, March 11, 2018

MCQs Set VI - Kinetics



Kinetics
1.     In 32 minutes, 75% of a first order reaction was completed. When was 50% of the reaction completed:-
a.      24 minutes
b.     16 minutes
c.      8 minutes
d.     4 minutes
2.     The reaction between X and Y is first order with respect to X and second order with respect to Y. If the concentration of X is halved and the concentration of  Y is doubled, the rate of reaction will be:-
a.      Same as initial value
b.     Double the initial value
c.      Three times the initial value
d.     Half the initial value
3.     In the reaction N2 + 3H2→2NH3, the rate of disappearance of H2 is1.8×10-5mol L-1s-1. Therefore, the rate of formation of ammonia is:-
a.      3.6×10-5mol L-1s-1
b.     1.2×10-5mol L-1s-1
c.      2.7×10-5mol L-1s-1
d.     1.8×10-5mol L-1s-1
4.     The unit of rate constant of a first order reaction is:-
a.      mol L-1s-1
b.     s-1
c.      s-1(mol L-1)-1
d.     s-1mol2L-2
5.     In the rate law given by: rate =k[A][B], the overall order of the reaction is :-
a.      1
b.     0
c.      2
d.     3
6.     For a reaction when k = 2.5×103 L mol-1s-1, then the order of the reaction is :-
a.      1
b.     2
c.      3
d.     0
7.     The half life in independent of initial concentration of reactants in :-
a.      Zero order reaction
b.     First order reaction
c.      Second order reaction
d.     Third order reaction
8.     For a first order reaction k = 2.5×10-4s-1, then the rate for initial concentration of 0.01mol/L is :-
a.      2.5×10-4 mol/L/s
b.     2.5×10-3 mol/L/s
c.      2.5×10-6 mol/L/s
d.     2.1×103mol/L/s
9.     For a reaction
2N2O5→ 4NO2 + O2
          If the concentration of NO2 increases by 5.2×10-3M in 100s, then the rate of reaction is:-
a.      1.3× 10-5  M/s
b.     0.5× 10-5  M/s
c.      7.6× 10-4  M/s
d.     2.5× 10-5  M/s
10.                         The half life of a first order reaction is 1min 40s. Calculate the rate constant.
a.      6.93×10-3 s
b.     6.93×10-3s-1
c.      4.95×10-3s
d.     1.73×10-3s-1
11.                        In a reaction, A + B → Product, rate is doubled when the concentration of B is doubled, and rate increases by a factor of 8 when the concentrations of both the reactants (A and B) are doubled, rate law for the reaction can be written as :-
a.     Rate = k[A] [B]
b.    Rate = k[A]2[B]
c.     Rate = k[A][B]2
d.    Rate = k[A]2[B]2
12.    The activation energy for a reaction at the temperature T K was                                                        found to be 2.303 RT J mol–1. The ratio of the rate constant to Arrhenius factor is :-
a.      10–1
b.     10–2
c.      2 × 10–3
d.     2 × 10–2
13.For a first order reaction (A) → products the concentration of A changes from 0.1M to 0.025 M in 40minutes.The rate of reaction when the concentration of A is 0.01 M is:
a.       1.73 × 10–5 M/min
b.      3.47 × 10–4 M/min
c.       3.47 × 10–5 M/min
d.      1.73 × 10–4 M/min
14.                        The rate of a chemical reaction doubles for every 10°C rise of temperature. If the temperature is raised by 50°C, the rate of the reaction increases by about
a.         64 times
b.        10 times
c.         24 times
d.        32 times
15.                         The rate of reaction increases with temperature due to
a.      Decrease in activation energy
b.     Increase in activation energy
c.      Increase in collision frequency
d.     Increase in concentration.
16.                        The rate constant of a first order reaction depends on
a.      The nature of the vessel
b.     Initial concentration of the reactant
c.      The temperature
d.     The time.
17.                         The rate law for the reaction RCl + NaOH → ROH + NaCl is given by n = k[RCl]. Therefore the rate of reaction will be
a.      Independent of the concentration of RCl
b.     Doubled on doubling the concentration of NaOH
c.      Unaffected by increasing the temperature.
d.     Halved when the concentration of RCl is halved.
18.                         Rate constant for a reaction is 10-3 s-1. Calculate the time after which 25% of the reactants remain.
a.      693s
b.     1386s
c.      6930s
d.     2029s
19.                         For the reaction A + B → C, it is found that doubling the concentration of A increases the rate by four times and doubling the concentration of B doubles the reaction rate. What is the overall order of reaction?
a.      4
b.     3/2
c.      3
d.     1
20.                         The slope in Arrhenius plot is equal to
a.      –Ea/2.303R
b.     Ea/R
c.      –R/2.303Ea
d.     None of the above.


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