Which of the following have identical bond order?

The cyanide ion, CN^- and N₂ are isoelectronic, But in contrast to CN^-, N₂ is chemically inert, because of

The molecules that will have dipole moment are

At 27^oC, hydrogen is leaked through a tiny hole into a vessel for 20 minutes. Another unknown gas at the same temperature and pressure as that of H₂ is leaked through the same hole for 20 minutes After the effusion of the gases the mixture exerts a pressure of 6 atmosphere. The hydrogen content of the mixture is 0.7 mole. If the volume of ther container is 3 litres, what is the molecular weight of the unknown gas?