Question

Match the salts underlined in Column A with the most suitable method of preparation given in Column B.

	Column A		Column B
(a)	\[\ce{ZnCl2 \text{from} Zn}\]	1.	Precipitation
(b)	\[\ce{KNO3 \text{from} KOH}\].	2.	Direct combination
(c)	\[\ce{CaCO3 \text{from} CaCl2}\].	3.	Displacement reaction
		4.	Neutralization

Answer 1

	Column A		Column B
(a)	\[\ce{ZnCl2 \text{from} Zn}\]	3.	Displacement reaction
(b)	\[\ce{KNO3 \text{from} KOH}\].	4.	Neutralization
(c)	\[\ce{CaCO3 \text{from} CaCl2}\].	1.	Precipitation

Explanation:

1. Displacement Reaction
   \[\ce{Zn + HCl -> ZnCl2 + H2}\]
   Displace H from HCl because zinc is more reactive than hydrogen.
2. Neutralization Reaction
   \[\ce{KOH + HNO3 -> KNO3 + H2O}\]
   \[\ce{Base + Acid -> Salt + water; Neutralization reaction}\]
3. Precipitation Reaction
   \[\ce{CaCl2 + Na2CO3 -> 2NaCl + CaCO3 ↓}\]
   Sodium chloride and a clacium carbonate precipitate follow from the double displacement reaction.