b
(b)The unit of rate constant shows that reaction is of first order. For first order reaction, half life is independent of initial conc. of the reactant.
Thus,
\({t_{1/2}} = \frac{{0.693}}{{0.69 \times {{10}^{ - 1}}}} = \frac{{0.693 \times 60}}{{0.69 \times {{10}^{ - 1}}}} = 600\,\sec \)