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

Which of the following statement$(s)$ is (are) correct?

Match the following columns:

Column-$I$	Column-$II$
$(1)$ Photon	$(A)$ Value of $4$ for $N$ shell
$(2)$ Electron	$(B)$ Probability density
$(3)$ $\psi^2$	$(C)$ Always $+$ value
$(4)$ Principal quantum number $(n)$	$(D)$ Represents wavelength and momentum

The statement that is $NOT$ correct is:

Which of the following violates the Aufbau principle and Hund's rule?

Among the following,the correct statement$(s)$ for electrons in an atom is(are):
$A$. Uncertainty principle rules out the existence of definite paths for electrons.
$B$. The energy of an electron in $2s$ orbital of an atom is lower than the energy of an electron that is infinitely far away from the nucleus.
$C$. According to Bohr's model,the most negative energy value for an electron is given by $n=1$,which corresponds to the most stable orbit.
$D$. According to Bohr's model,the magnitude of velocity of electrons increases with increase in values of $n$.