For the Balmer series in the spectrum of H atom,
$$\overline \nu = {R_H}\left\{ {{1 \over {n_1^2}} - {1 \over {n_2^2}}} \right\}$$, the correct statements among (I) to (IV) are :
(I) As wavelength decreases, the lines in the series converge
(II) The integer n₁ is equal to 2
(III) The lines of longest wavelength corresponds to n₂ = 3
(IV) The ionization energy of hydrogen can be calculated from wave number of these lines

The number of orbitals associated with quantum number n = 5, m_s = +$${1 \over 2}$$ is :

The electrons are more likely to be found :

The group number, number of valence electrons, and valency of an element with atomic number 15, respectively, are: