Alpha-particles that come closer to the nucleus:

$A$ certain metal has a work function of $\Phi = 2 \ eV$. It is irradiated first with $1 \ W$ of $400 \ nm$ light and later with $1 \ W$ of $800 \ nm$ light. Among the following,the correct statement is
[Given: Planck constant $(h) = 6.626 \times 10^{-34} \ J \ s$;
Speed of light $(c) = 3 \times 10^8 \ m \ s^{-1}$ ]

In the transition of an electron in an atom,its kinetic energy changes from $y$ to $y/4$. The change in potential energy $(P.E.)$ will be:

The potential energy of an electron in the third excited state of $He^{+}$ ion is ............. $eV$.

If the wavelength of an electromagnetic radiation is $2000 \ \text{Å}$, what is its energy in ergs?

Which one of the following statements is not correct?