The bond order of $HeH^{+}$ is

$He_{2}$ molecule is not possible. Explain.

In which of the following transformations,the bond order has increased and the magnetic behaviour has changed?

The main axis of a diatomic molecule is $Z$. The orbitals $p_{x}$ and $p_{y}$ overlap to form:

Among the following molecules / ions $C_2^{2-}, N_2^{2-}, O_2^{2-}, O_2$,which one is diamagnetic and has the shortest bond length?

Assertion : Fluorine molecule has bond order one.
Reason : The number of electrons in the antibonding molecular orbitals is two less than that in bonding molecular orbitals.