Identify the CORRECT statement about the chlor-alkali process:

The correct statement is: Hydrogen gas is formed at the cathode and chlorine gas at the anode.

Step-by-Step Explanation:

The chlor-alkali process is an industrial method used for the electrolysis of an aqueous solution of sodium chloride, commonly known as brine. During this electrolytic process, three highly useful products are formed: sodium hydroxide ($\mathrm{NaOH}$), chlorine gas (${\mathrm{Cl}}_2$), and hydrogen gas ($H_2$).

Let's understand the chemical reactions occurring at each electrode during the electrolysis of brine:

1. Dissociation in aqueous solution:
When sodium chloride dissolves in water, it dissociates into ions:
$\mathrm{NaCl}\to {\mathrm{Na}}^{+}+{\mathrm{Cl}}^{-}$
Water also auto-ionizes slightly:
$H_{2}O\rightleftharpoons H^{+}+{\mathrm{OH}}^{-}$

2. Reaction at the Anode (Positive Electrode):
Negatively charged chloride ions (${\mathrm{Cl}}^{-}$) and hydroxide ions (${\mathrm{OH}}^{-}$) are attracted to the anode. Chloride ions are preferentially oxidized because of their lower discharge potential:
$2{\mathrm{Cl}}^{-}\to {\mathrm{Cl}}_2+2e^{-}$
Thus, chlorine gas (${\mathrm{Cl}}_2$) is liberated at the anode.

3. Reaction at the Cathode (Negative Electrode):
Positively charged sodium ions (${\mathrm{Na}}^{+}$) and hydrogen ions ($H^{+}$) are attracted to the cathode. Hydrogen ions are preferentially reduced due to their higher reduction potential compared to sodium ions:
$2H^{+}+2e^{-}\to H_2$
Thus, hydrogen gas ($H_2$) is liberated at the cathode.

4. Formation of Sodium Hydroxide:
The remaining sodium ions (${\mathrm{Na}}^{+}$) and hydroxide ions (${\mathrm{OH}}^{-}$) combine in the solution to form sodium hydroxide ($\mathrm{NaOH}$) near the cathode:
${\mathrm{Na}}^{+}+{\mathrm{OH}}^{-}\to \mathrm{NaOH}$

Therefore, we can verify the options:
- The process is used to prepare $\mathrm{NaOH}$, not ${\mathrm{Na}}_2{\mathrm{CO}}_3$ (which is prepared by the Solvay process).
- Hydrogen gas is formed at the cathode and chlorine gas at the anode, which is correct.
- Sodium hydroxide is generated near the cathode, not near the anode.