What is the formal charge of oxygen atoms in carbon monoxide?

Which of the following molecules contains both ionic and covalent bonds?

The number of molecules from the following which contain only two lone pairs of electrons is $........$.
$H_2O, N_2, CO, XeF_4, NH_3, NO, CO_2, F_2$

Select the correct order:
$(a)$ $CO < CO_2 < CO_3^{2-}$ $\Rightarrow$ Bond length
$(b)$ $O_2 < O_3 < O_2^{2-}$ $\Rightarrow$ Bond length
$(c)$ $N_2 < N_2^+$ $\Rightarrow$ Bond energy

The correct order of $C-O$ bond length among $CO, CO_3^{2-}, CO_2$ is

Which of the following odd electron species is planar?