A first order reaction is found to have rate constant, \(k = 3.5 × 10^{-4} s^{-1}\). Its half life will be:

\(198 × 10 s\)

The correct answer is option 1. \(198 × 10 s\).

Given,

Rate constant for the first order reaction, \(k = 3.5 × 10^{-4}s^{-1}\)

We know, for a first order reaction,half-life,

\(t_{1/2} = \frac{0.693}{3.5 × 10^{-4}s^{-1}}\)

or, \(t_{1/2} = 1980s\)

or, \(t_{1/2} = 198 × 10 s\)