(a)A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour. (i) What type of colour change do you observe?
(ii) Identify the type of reaction.
(iii) Write a word equation for the above change.

(i) blue colour fades away

(ii) Single replacement

(iii) copper sulphate + iron iron sulphate + copper

Explanation:

Single replacement reaction is a chemical reaction in which more reactive element displaces the less reactive element from its salt solution.

 Here iron being more reactive than copper can easily displace copper from its salt solution and form iron sulphate and copper in elemental form.

The blue colour of the copper sulphate solution fades away.

The word equation is :

copper sulphate + iron iron sulphate + copper

the answer for sodium is 0.186

the answer for rubidium is 0.251