Give reasons for the following.
- Aluminium foils are used to wrap food items.
- Immersion rods for heating liquids are made up of metallic substances.
- Copper cannot displace zinc from its salt solution.
- Sodium and potassium are stored in kerosene.
Answer:
- Aluminium foils are used to wrap food items because aluminium metal is malleable. Therefore, it can be beaten into thin foils.
- Metals are good conductors of heat and electricity. Therefore, immersion rods for heating liquids are made of metallic substances.
- A metal can displace a less reactive metal from its salt in an aqueous solution.
But zinc is more reactive than copper. Therefore, copper cannot displace zinc from its salt solution.
Cu(s) + ZnSO 4(aq)---------► No reaction - Sodium and potassium are stored in kerosene because they are highly reactive elements. They can easily catch fire even when in contact with air.