(a) Draw the structures of the following molecules: (i) H3PO2 (ii) ClF3 (b) Explain the following observations: (i) Nitrogen is much less reactive than phosphorus. (ii) Despite having greater polarity, hydrogen fluoride boils at a lower temperature than water. (iii) Sulphur has a greater tendency for catenation than oxygen in the same group.

b)i) Nitrogen molecule exists as N2 gas in which two nitrogen atoms are triply bonded so the presence of a triple bond makes the nitrogen bond strong and less reactive whereas phosphorus exists as P4 molecule, where each phosphorus molecule is singly bonded hence it is weak and more reactive.
ii) Even though HF is polar and having hydrogen bonding it shows a less boiling point because 1 HF molecule forms 1 hydrogen bond which can be broken down easily and can be boiled at a low temperature whereas in H2O one molecule of H2O forms 2 hydrogen bonds so much heat is required to break them.
iii) Oxygen is small in size and the lone pair of oxygen atoms repel the bond pair of oxygen atoms but in sulphur the lone pair of electrons repel the bond pair of electrons to a smaller extent. Sulphur naturally exists as S8 molecule, on heating sulphur these bonds break and long chains are formed. Hence sulphur has a greater tendency for catenation than oxygen.