Question

In a first order reaction, the concentration of the reactant is reduced to 25% in one hour. The half-life period of the reaction is ____________.

Options

• 30

• 180

• 1800

• 3600

Answer 1

In a first order reaction, the concentration of the reactant is reduced to 25% in one hour. The half-life period of the reaction is 1800.

Explanation:

For a first order reaction, after one half-life period, the concentration will be reduced to 50%.

After another half-Life period, the concentration will be reduced to 25%.

∴ 2 `"t"_(1//2)` = 1 hr ........(given) 

`"t"_(1//2) = 1.2  "hr" xx (60  "min")/(1  "hr") xx (60  "s")/(1  "min")` = 1800 seconds