Give reasons for the following :
(i) Covalent bonds are directional while ionic bonds are non-directional.
(ii) Water molecule has bent structure whereas carbon dioxide molecule is linear.
(iii) Etyne molecule is linear.

Explanation

(i) Covalent bonds are formed as a frsilt of the overlap of the atomic orbitals. Since the atomic orbitals are directional, covalent bonds are also directional in nature. On the other hand, ionic bonds are formed simple by electron transfer and these are non-idrectinal in nature. For details consult sections 4.3 and 4.6
In `H_(2)O` molecule, oxygen atom is `sp^(3)` hybridised. The shape of momecule is that of distorted tetahedron or it is angular or bent since there are two lone electron pairs on oxygen atom In `CO_(2)` molecule, carbon atom is sp hybridised. Therefore, the shape of molecule is linear.
(iii) For the shape of ethyne molecule, consult section 4.20.