Question

Half-life period for a reaction at an initial concentration of $0.1M$ and $0.01M$ are $5$ and $50$ respectively. The order of the reaction is:

• A. $0$
• B. $1$
• C. $2$
• D. $3$

Answer 1

The correct option is C $2$

When the initial concentration is reduced from $0.1M$ to $0.01M$, the half-life period of the reaction increases from $5$ minutes to $50$ minutes.

Thus, when the initial concentration is reduced to one-tenth, the half-life period becomes $10$ times.

Hence, the half-life period is inversely proportional to the initial concentration

$(t_{1/2}\propto \frac{1}{A})$.

This is true for the second-order reaction.