Consider the following statements :
${\mathrm{S}}_1$ : The ionization energy of molecular nitrogen is greater than that of atomic nitrogen.
${\mathrm{S}}_2$ : The ionization energy of molecular oxygen is less than that of atomic oxygen.

${\mathrm{S}}_3$: Between ${\mathrm{SiCl}}_4\text{ and }{\mathrm{CCl}}_4$, only ${\mathrm{SiCl}}_4$ reacts with water because ${\mathrm{SiCl}}_4$ is ionic and ${\mathrm{CCl}}_4$ is covalent.

${\mathrm{S}}_4$ : ${\mathrm{O}}_2^{-}$ is paramagnetic and has bond order less than ${\mathrm{O}}_2$.

Select the correct set of statements.

Statement 3 is incorrect while all other are correct.

The ionization energy of molecular nitrogen is greater than that of atomic nitrogen, the ionization energy of molecular oxygen is less than that of atomic oxygen and ${\mathrm{O}}_2^{-}$- is paramagnetic and has bond order less than ${\mathrm{O}}_2$ statements are correct.

The following bonding molecular orbitals of the nitrogen molecule are fully filled:
$\sigma 1s^2{\sigma }^{*}1s^2\sigma 2s^2{\sigma }^{*}2s^2\pi 2p_x^2\pi 2p_y^2\sigma 2p_z^2$
and atomic nitrogen has the following half-filled p-orbitals:
$1s^{2}2s^{2}2p^3$
Since the energy of the nitrogen molecule's bonding molecular orbitals is lower than the energy of the nitrogen atom's atomic orbital. As a result, it possesses more initial ionization energy than an atom of nitrogen.
In ${\mathrm{O}}_2$, antibonding electrons have the maximum energy. Consider what antibonding actually means: it doesn't merely imply an orbital with a higher energy than a bonding orbital. Regarding the AOs that make up its constituents, it is antibonding. In general, bound electrons are more difficult to remove from an atom than valence electrons.
Hence, option C is correct.