The $\sigma _{2s}^*$ molecular orbital has a nodal plane similar to which of the following orbitals?

Explain the linear combination of atomic orbitals $(LCAO)$ with a suitable example.

How many of the following species have the bond order $2$?
$C_2, B_2^{2-}, N_2^{2+}, CN^{+}, NO^{-}, O_2, C_2^{+}$

What is the bond order of $O_2^{2-}$?

Consider the following changes $I$ and $II$ as shown in the figure. The correct statements about these changes $(I)$ and $(II)$ in accordance with $MO$ theory are:
$A$) In $(I)$ bond order increases by $0.5$ from the existing value.
$B$) In $(II)$ bond order decreases by $0.5$ from the existing value.
$C$) In both $(I)$ and $(II)$ magnetic property is changed.
$D$) In both $(I)$ and $(II)$ magnetic property is not changed.

Which of the following species is the least stable?