Give reasons for the following :
(a) Aluminium foils are used to wrap food items.View Answer
Aluminium foils are used to wrap food items.
To wrap food items, we need a thin sheet.
Aluminium foils are used to wrap food items because aluminium is malleable
Which means it can be beaten into thin sheets which can be used to wrap food items
(b) Immersion rods for heating liquids are made up of metallic substances.View Answer
Immersion rods for heating liquids are made up of metallic substances.
Metals are good conductors of heat and electricity. Immersion rods for heating liquids are made up of metallic substances because being good conductors of heat, they'll be able to transfer heat quickly
(c) Copper cannot displace zinc from its salt solution.View Answer
Copper cannot displace zinc from its salt solution.
In displacement reaction,
More reactive metals displace less reactive metals from their compounds
Here, Zinc is more reactive metal than Copper
Thus, Copper cannot displace Zinc from its salt solution
Copper + Zinc Sulphate → No displacement reaction
(d) Sodium and potassium are stored in kerosene.View Answer
Sodium and potassium are stored in kerosene.
Sodium and potassium are the most reactive metals, and they catch fire even when exposed to small amounts of air.
To eliminate such reactions, it is stored in kerosene.