In which of the following molecules do the $\pi 2p_x$ and $\pi 2p_y$ orbitals fill after the $\sigma 2p_z$ molecular orbital?

The molecule having one unpaired electron is

The energy of $\sigma 2p_z$ molecular orbital is greater than $\pi 2p_x$ and $\pi 2p_y$ molecular orbitals in nitrogen molecule. Write the complete sequence of energy levels in the increasing order of energy in the molecule. Compare the relative stability and the magnetic behaviour of the following species : $N_2, N_2^+, N_2^-, N_2^{2+}$

What is the correct order of bond lengths in the following molecules? $I. O_2, II. O_2^+, III. O_2^-, IV. O_2^{2-}$

During the formation of molecular orbitals from atomic orbitals,the electron density .....

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.