1. Phosphine has lower boiling point than ammonia. Why?
2. State allotropic properties of group 15 elements.
3. On moving down the group atomic radius increase and decrease in period. Why?
4. What is ionisation enthalpy? Explain the trends of ionisation enthalpy of group 15 elements in group and period.
5. What is the most common valency of 15th group elements?
6. Nitrogen is inert at room temperature. Give reason.
7. Which is most electronegative element in 15th group?
8. The melting point of antimony and bismuth decrease. Explain.
9. Why elements of group 15 generally shows lower ionisation enthalpy to the corresponding period of group 14?
10. Why nitrogen is used for producing inert atmosphere?