Arrange the following in the decreasing order of their bond enthalpy: $H_2, O_2, N_2$.

The number of $S-S$ bonds in sulphur trioxide trimer $S_3O_9$ is

Identify the correct statements from the following.
$(I)$ $SnCl_2$ is ionic,but $SnCl_4$ is covalent in nature.
$(II)$ All linear diatomic molecules have zero dipole moment.
$(III)$ Both $NO$ and $O_2$ are paramagnetic.

Which of the following statements is correct?

Which of the following statements is incorrect?

The correct formula used to determine the formal charge $(Q_{f})$ on an atom in the given Lewis structure of a molecule or ion is ($V=$ number of valence electrons in free atom,$U=$ number of unshared electrons on the atom,$B=$ number of bonds around the atom)