(4) kinetic energy increases, but potential energy and total energy both decrease
In the given transition, principal quantum number (n) decreases. Now the speed of the electron in the nth orbit, (vn), is inversly proportional to n. Hence, when n decreases, vn and, therefore, the kinetic energy of the electron, increases.
We also know
Total energy = - K.E and
Potential energy = -2 K.E
Due to -ve sign, in the expression for T.E and P.E; both these energies decrease when n decreases.