modern physics Questions

According to Einstein’s photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal vs the frequency of the incident radiation gives a straight line whose slope:

The work function of a substance is $4.0\text{eV}$. Then the longest wavelength of light that can cause photoelectron emission from this substance is approximately:

A nucleus disintegrates into two nuclear parts which have their velocities in the ratio $2:1$. The ratio of their nuclear sizes will be:

The binding energy per nucleon of deuteron (${}_1^2\text{H}$) and helium nucleus (${}_2^4\text{He}$) is $1.1\text{MeV}$ and $7\text{MeV}$ respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is:

An $\alpha$ -particle of energy $5\text{MeV}$ is scattered through $180^{\circ }$ by a fixed uranium nucleus ($Z=92$). The distance of the closest approach is of the order of: