Which of the following molecules has unequal bond lengths?

Apart from tetrahedral geometry,another possible geometry for $CH_4$ is square planar with the four $H$ atoms at the corners of the square and the $C$ atom at its centre. Explain why $CH_4$ is not square planar?

In which of the following is the $O-N-O$ bond angle maximum?

Which of the following species is planar?

Among the following,the pair in which the two species are not isostructural is

In $NO_3^{-}$ ion,the number of bond pairs and lone pairs of electrons on the nitrogen atom are