Give reasons for the following.
(a) Aluminium foils are used to wrap food items.
(b) Immersion rods for heating liquids are made up of metallic substances.
(c) Copper cannot displace zinc from its salt solution.
(d) Sodium and potassium are stored in kerosene.
Answers
Answer:
(a)Aluminium is malleable, soft and does not react with food items, so it is used to wrap food items. (b) Immersion rods for heating liquids are made up of metallic substances because metals are good conductors of heat and electricity. The immersion rod needs electric supply to get heated and; in turn; to heat liquids.
(c)Copper is less reactive than zinc and so placed below zinc in the reactivity series of metals. ... Hence, copper cannot displace zinc from its salt solution.
(d)Sodium and Potassium are highly reactive metals and react vigorously with the oxygen, carbon dioxide and moisture present in the air such that it may even cause a fire. To prevent this explosive reaction, Sodium is kept immersed in kerosene because Sodium doesn't react with kerosene
a. Aluminium is malleable, soft and does not react with food items, so it is used to wrap food items.
b. Immersion rods for heating liquids are made up of metallic substances because metals are good conductors of heat and electricity. The immersion rod needs electric supply to get heated and; in turn; to heat liquids.
c. Copper is less reactive than zinc and so placed below zinc in the reactivity series of metals. A less reactive metal cannot displace a more reactive metal from its salt solution. Hence, copper cannot displace zinc from its salt solution.
d. Sodium and Potassium are highly reactive metals and react vigorously with the oxygen, carbon dioxide and moisture present in the air such that it may even cause a fire. To prevent this explosive reaction, Sodium is kept immersed in kerosene because Sodium doesn't react with kerosene.