\( \mathrm{A \rightarrow B} \)
The molecule A changes into its isomeric form B by following a first order kinetics at a temperature of \( 1000 \,\text{K} \). If the energy barrier with respect to reactant energy for such isomeric transformation is \( 191.48 \,\text{kJ mol}^{-1} \) and the frequency factor is \( 10^{20} \), the time required for \( 50\% \) molecules of A to become B is __________ picoseconds (nearest integer). \([R = 8.314 \,\text{J K}^{-1} \text{ mol}^{-1}]\)