Question

A solution of sodium sulphate in water is electrolysed using electrodes. The product at cathode and anode respectively .
$\left( A \right){H_2},{O_2}$
$\left( B \right){O_2},{H_2}$
$\left( C \right){O_2},Na$
$\left( D \right){O_2},S{O_2}$

Answer 1

Hint : Anode is a negative electrode which releases electrons to the external circuit . A cathode is the positive electrode which absorbs electrons from the circuit . These two electrodes are present in the process of electrolysis .

Complete step by step solution
Electrolysis is a process in which the ionic compounds are decomposed into its elements when electric current is passed. The cations are reduced at cathode and anions are oxidised at the anode . This process occurs in an electrolytic cell in which two electrodes are connected to a direct current source .
The minimum potential needed for the electrolysis depends upon the ions to absorb or release electrons . The sum of the potential required for both reduction and oxidation is called cell potential.
A solution of sodium sulphate in water is electrolysed using inert electrodes , the product at cathode and anode will be ${H_2},{O_2}$ .
$2{H^ + } + 2{e^ - } \to {H_2} \uparrow$
Here , the hydrogen has a higher reduction than sodium so it will be liberated at cathode .
$4O{H^ - } \to 2{H_2}O + {O_2} + 4{e^ - }$
similarly hydroxide ions have lower discharge than sulphate ions so it will liberate on the anode .
Hence , option $\left( A \right)$ is correct .

Additional Information
Faraday's first law of electrolysis : it states that chemical decomposition due to flow of current is directly proportional to the quantity of electricity passed through it.
$m = ZQ$
Where $m$ is mass of chemical decomposition , $Z$ is constant and $Q$ is quantity of electricity .
Faraday's second law of electrolysis : when the same quantity of electricity is passed through several electrolysis , the mass of substance deposited is proportional to respective equivalent weight .

Note:
Electrolysis depends on the nature of electrodes and electrolyte , nature of electrode potential present and overvoltage at the electrodes . whenever there are more than one ions present then they will compete with each other for reduction and oxidation just like in the above case .