JEE · NEET Previous Year Question

The half life of a stream of radioactive particles moving along a straight path with a constant kinetic energy of $4\text{eV}$ is 1 minute. The percentage of particles which decay before travelling a distance of $3.6\text{km}$ is (Mass of the radioactive particles $=3.2\times {10}^{-21}\text{kg}$ and charge of the electron $=1.6\times {10}^{-19}C$ ).

Topic: JEE PYQ

Answer: A. Full step-by-step solution below.