Which of the following molecules is not paramagnetic in nature?

The wave functions of $1s$-orbitals of two hydrogen atoms are $\psi_A$ and $\psi_B$. $\psi_A$ and $\psi_B$ are linearly combined to form two molecular orbitals ($\sigma$ and $\sigma^*$). Which of the following statements are correct?
$I$. $\sigma^*$ is equal to $(\psi_A - \psi_B)$.
$II$. In $\sigma$-orbital,one nodal plane is present in between two nuclei.
$III$. The energy of $\sigma$-orbital is lower than the energy of $\sigma^*$-orbital.

If $N_x$ is the number of bonding orbitals of an atom and $N_y$ is the number of antibonding orbitals,then the molecule/atom will be stable if

According to $MO$ theory,the number of species/ions from the following having identical bond order is $.........$
$CN^{-}, NO^{+}, O_{2}, O_{2}^{+}, O_{2}^{2+}$

Which of the following is not paramagnetic?

Write the important conditions required for the linear combination of atomic orbitals to form molecular orbitals.