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.
Answers
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.
2. Some metals react with water to produce metal hydroxides which are basic in nature. Non metals react with oxygen to produce non- metallic oxides which are acidic in nature. 5] Metals react with acids and produce metal salts and hydrogen gas. Generally, non - metals do not react with acids.
3.(a) 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.
3.(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.
4.(c) Uses of some common metals and non-metals are as follows. Metals Iron is used for making automobiles, machinery, pipes, containers, nails, etc. Gold and silver are used for making jewellery. Copper is used for making electrical wires, cooking utensils,
Answer:
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