Which of these is least likely to act as a Lewis base?

Number of $\pi$ electrons in cyclobutadienyl anion $({C_4}{H_4})^{2-}$ is

Which of the following pairs have the same bond angles?
$(a) BF_3, BCl_3$
$(b) PO_4^{3-}, SO_4^{2-}$
$(c) BF_3, PF_3$
$(d) NO_2^+, N_2O$
$(e) N_3^-, NO_2$
Select the correct option:

The ratio of lone pair of electrons to bond pair of electrons in an ozone $(O_3)$ molecule is

Number of molecules from the following which are exceptions to the octet rule is. . . .
$CO_2, NO_2, H_2SO_4, BF_3, CH_4, SiF_4, ClO_2, PCl_5, BeF_2, C_2H_6, CHCl_3, CBr_4$

If compound $MX_4$ is non-polar and has no lone pair at the central atom,then the bond angle $\angle XMX$ in the compound may be: