Question

explain why an aqueous solution of sodium sulphate is neutral while an aqueous solution of sodium carbonate is basic in nature.

Answer 1

Because Sodium sulphate  salt is made by reaction of sulphuric acid (strong acid) the sodium hydroxide (strong base) , thus on combining the opposite effects of acid and base neutralize each others effect completely leading to the formation of a neutral salt.
Sodium carbonate salt is made of reaction of carbonic acid and sodium hydroxide . on combining the basic character will be more as a week acid can not neutralize a strong base completely . so the salt formed is basic in nature.

Answer 2

"Strong base is NaOH and weak acid is $\mathrm{H}_{2} \mathrm{CO}_{3}$

Sodium sulphate is a neutral salt because it is made from the strong acid and strong base.

$2{ NaOH }+{ H }_{ 2 }{ SO }_{ 4 }\rightarrow { Na }_{ 2 }{ SO }_{ 4 }+2{ H }_{ 2 }{ O }$

Here in the above chemical reaction, strong acid is $\mathrm{H}_{2} \mathrm{SO}_{4}$and strong base is NaOH

Sodium carbonate is a basic salt because it is made from a strong base and a weak acid.

$2{ NaOH }+{ H }_{ 2 }{ CO }_{ 3 }\rightarrow { Na }_{ 2 }{ CO }_{ 3 }+2{ H }_{ 2 }{ O }"$