Unit VII: Chemical Kinetics - Online Test

Q1. What is the activation energy for a reaction if its rate doubles when the temperature is raised from 200K to 400K? (R = 8.314 JK-1mol-1)
Answer : Option C
Explaination / Solution:

T1 = 200K ; k = k1

T2 = 400K ; k = k2 = 2k1



Q2.  This reaction follows first order kinetics. The rate constant at particular temperature is 2.303 × 102 hour1 . The initial concentration of cyclopropane is 0.25M.  What will be the concentration of cyclopropane after 1806 minutes? (log 2 = 0.3010)
Answer : Option B
Explaination / Solution:



Q3. For a first order reaction, the rate constant is 6.909 min-1.the time taken for 75% conversion in minutes is
Answer : Option B
Explaination / Solution:




Q4. In a first order reaction x → y ; if k is the rate constant and the initial concentration of the reactant x is 0.1M, then, the half life is
Answer : Option C
Explaination / Solution:




Q5.

Predict the rate law of the following reaction based on the data given below

2A + B → C + 3D



Answer : Option B
Explaination / Solution:




Q6.

Assertion: rate of reaction doubles when the concentration of the reactant is doubles if it is a first order reaction.

Reason: rate constant also doubles
Answer : Option C
Explaination / Solution:

For a first reaction, If the concentration of reactant is doubled, then the rate of reaction also doubled.

Rate constant is independent of concentration and is a constant at a constant temperature,


Q7. The rate constant of a reaction is 5.8 × 10−2 s−1 . The order of the reaction is
Answer : Option A
Explaination / Solution:

The unit of rate constant is s-1 and it indicates that the reaction is first order.

Q8. For the reaction  N2O5(g) → 2NO2 (g) + ½ O2(g), the value of rate of disappearance of N2O5 is given as 6.5 × 10-2 mol L-1 s-1. The rate of formation of NO2 and O2 is given  respectively as
Answer : Option C
Explaination / Solution:




Q9. During the decomposition of H2O2 to give dioxygen, 48 g O2 is formed per minute at certain point of time. The rate of formation of water at this point is
Answer : Option D
Explaination / Solution:


no of moles of oxygen = (48/32) = 1.5 mol

rate of formation of oxygen = 2 ×1.5 = 3 mol min-1


Q10. If the initial concentration of the reactant is doubled, the time for half reaction is also doubled. Then the order of the reaction is
Answer : Option A
Explaination / Solution:

For a first order reaction t1/2 is independent of initial concentration .i.e., n ≠ 1; for such cases