Question

A first-order reaction is $50$% completed in $1.26\times {10}^{14}sec$. How much time would it take for $100$% completion?

• A. $1.26\times {10}^{15}sec$
• B. $2.52\times {10}^{14}sec$
• C. $2.52\times {10}^{28}sec$
• D. Infinite

Answer 1

The correct option is D Infinite

The time taken for half the reaction to complete i.e., the time in which the concentration of a reactant is reduced to half of its original value is called half-life period of the reaction.

But it is impossible to perform 100% of the reaction. the whole of the substance reacts because, in very half-life, 50% of the substance reacts. Hence, time taken 100% completion of a reaction is infinite.

Therefore, option D is correct.