Question

State the reason for the following:
(i) Aluminium oxide is called an amphoteric oxide.
(ii) An iron strip dipped in a blue copper sulphate solution turns the blue solution pale green.
(iii) Hydrogen gas is not evolved when most metals react with nitric acid.
(iv) Calcium does not occur in free state in nature.
(v) Sodium or potassium metals are kept immersed under kerosene.

Answer 1

Answer:

1 because it react with both acid as well as base

2 iron is more reactive then copper

3 only in the case of mangese and magnesium Hydrogen gas is evolved

if except these metal if nitric acid then hydrogen gas become water

4 calcium does not kept in free because of its reactivity

5 because of its high reactivity

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Answer 2

Reason for the given questions:

• Aluminium oxide is known as 'amphoteric oxide' due to its reaction with both acids and bases.
• The iron strip which dipped in the "blue copper sulphate solution" turned into the "blue solution pale green". This is due to the fact that there is "formation of iron sulphate" takes place inside solution.
• When metals reacts with the nitric acid, it is oxidised by nitrate ion and not by hydrogen ion.
• Calcium doesn't occur in any 'free state' in nature, because it is "highly reactive in nature".
• Sodium and potassium metals are reactive and act violently in presence of air.

To know more:

Why Aluminium oxide is called as amphoteric oxide

https://brainly.in/question/2708571

State reason calcium does not occur free in nature.

https://brainly.in/question/2751474