For a zero-order reaction A → Products, the rate of the reaction is 10 mol L–1 min–1 at time t1 = 2 minutes. What will be the rate (in mol L–1 min–1) at time t2 = 12 minutes?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 10
In a zero order reaction the rate is proportional to the zero power of the reactant concentration:
\( \displaystyle \text{Rate}=k\,[\ce{A}]^0=k \)
The rate equals the rate constant and is independent of the concentration of A. The concentration of A falls between 2 min and 12 min, but this does not change the rate, which stays constant until the reactant is used up.
\( \displaystyle \text{Rate at } t_2=\text{Rate at } t_1=10\,\mathrm{mol\,L^{-1}\,min^{-1}} \)
NCERT (2026-27 edition):
3.2.3 Order of a Reaction – “Order of a reaction can be 0, 1, 2, 3 and even a fraction. A zero order reaction means that the rate of reaction is independent of the concentration of reactants.”