Question

VII. Long Answer Questions.
1. How do metals react with water? Describe reaction between sodium and
water through an activity. Also mention the reactions of potassium, calcium
and magnesium with water separately.
2. How do metals and non-metals react with acids? Describe the rate of
reaction of a dilute acid with different metals through an activity.
3. (a) What do you mean by displacement reaction? Describe them with some
examples.
(b) How do metals react with bases? Describe with an example.
(c) Discuss uses of some common metals and non-metals.​

Answer 1

Answer:

1)  Metals react with water and produce a metal oxide and hydrogen gas. ... Calcium starts floating because the bubbles of hydrogen gas formed stick to the surface of the metal. Magnesium does not react with cold water. It reacts with hot water to form magnesium hydroxide and hydrogen.

3a) Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. Both metals and non-metals take part in displacement reactions. Example : Reaction of iron nails with copper sulphate solution.

b) Reaction of Base with Metals:

When alkali (base) reacts with metal, it produces salt and hydrogen gas. Example: Sodium hydroxide gives hydrogen gas and sodium zincate when reacts with zinc metal. Sodium aluminate and hydrogen gas are formed when sodium hydroxide reacts with aluminium metal.

(c) Discuss uses of some common metals and non-metals.​

• Copper is used for making electrical wires, cooking utensils, etc.
• Zinc is mainly used as a protective coating for iron.
• Aluminium is used for making electrical cables, packaging, cooking utensils, etc.
• Non-metal essential for our life which  all living beings inhale during breathing,
• Non-metals used in fertilisers to  enhance the growth of plants,
• Non-metal used in water purification
• process,
• Non-metal used in the purple  coloured solution which is applied  on wounds as an antiseptic,
• Non-metals used in crackers.