Question

Explain why:
(1) Mercury loses its meniscus in contact with ozone.

(2) Halogens are coloured and the colour deepens on moving down in the group from fluorine to iodine.

(3) Hydride of sulphur is a gas while hydride of oxygen is a liquid.

Answer 1

(1) This is due to the formation of mercurous oxide (Hg₂O) which dissolves in mercury.

(2) This is because halogen molecules (X₂) absorb light in the visible region and transmit complementary colors. This is because moving from fluorine to iodine ionization enthalpy decreases.

(3) This is because in H₂S there are weak Van der Waals forces of attraction but in H₂O there are strong intermolecular H-bonds.