Question

Give reasons :

(a) A gas can fill the whole vessel in which it is enclosed.

(b) What do you observe when barium chloride solution is mixed with sodium sulphate solution ?

Answer 1

(a) Because, in gases, the molecules are free to move.
They are not stuck to each other and the intermolecular force of attraction is least in the gases. So the
gas almost lled the whole vessel in which it is enclosed.

(b) On mixing a solution of barium chloride with sodium sulphate, a white precipitate of barium sulphate is immediately formed. It is an example of double displacement reaction. These reactions are ionic in nature. The reactants changes into ions when dissolved in water and there is an exchange of ions in solution.