Question

Match the items given in Column I with examples given in Column II.

Column I	Column II
(i) Hydrogen bond	(a) \[\ce{C}\]
(ii) Resonance	(b) \[\ce{LiF}\]
(iii) Ionic solid	(c) \[\ce{H2}\]
(iv) Covalent solid	(d) \[\ce{HF}\]
	(e) \[\ce{O3}\]

Answer 1

Column I	Column II
(i) Hydrogen bond	(d) \[\ce{HF}\]
(ii) Resonance	(e) \[\ce{O3}\]
(iii) Ionic solid	(b) \[\ce{LiF}\]
(iv) Covalent solid	(a) \[\ce{C}\]

Explanation:

(i) In hydrogen fluoride \[\ce{HF}\], hydrogen forms strong hydrogen bonds with fluorine because of the electronegativity of fluorine. Fluorine is more electronegative than hydrogen and thus the electrons in fluorine are more stabilized and they cannot be easily donated to an acceptor.

(ii) Ozone is a neutral molecule which is stabilized through resonance. The negative charge created by an extra electron is delocalized by resonance through terminal oxygen atoms.

(iii) In lithium fluoride \[\ce{LiF}\], the lithium metal has a positive charge \[\ce{(+ 1)}\] and is a cation. The fluoride ion has a negative charge \[\ce{(- 1)}\] and is an anion. These two oppositely charged ions are held together by an ionic bond.

(iv) Carbon is a known covalent solid. The two allotropes of carbon, diamond and graphite are covalent network solids with different geometries. Due to the presence of covalent bonds in graphite and diamond, they have very high melting points and are poor conductors of heat and electricity.