Which of the following graphs represents one node?

The statement that is $NOT$ correct is:

In $H$ atom,an orbit has a diameter of about $16.92 \ \mathring{A}$. What is the maximum number of electrons that can be accommodated in this orbit?

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 $n$.

When the excited electron of a $H$ atom from $n=5$ drops to the ground state,the maximum number of emission lines observed are $.......$

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