\(2SO_2 (g) + O_2 (g) \overset{V_2O_5}{\longrightarrow} 2SO_3 (g)\,     \ \Delta H = -196.6\text{kJ mol}^{-1} \)

For the above given reaction, identify the incorrect statement from the following

The forward reaction leads to an increase in volume

The correct answer is option 3. The forward reaction leads to an increase in volume.

Let us analyze the given reaction and statements:

\[2SO_2 (g) + O_2 (g) \overset{V_2O_5}{\longrightarrow} 2SO_3 (g)\, \ \Delta H = -196.6\text{ kJ mol}^{-1}\]

Statements:

(1) It is an exothermic reaction:
The negative value of \(\Delta H\) (-196.6 kJ/mol) indicates that the reaction releases heat. Therefore, Statement (1) is correct.

(2) It is a reversible reaction:
The presence of the reversible arrow (\(\overset{V_2O_5}{\longrightarrow}\)) indicates that the reaction is reversible. So, Statement (2) is correct.

(3) The forward reaction leads to an increase in volume:
To determine the change in volume, we need to consider the stoichiometry of the reaction. The reaction involves two moles of \(SO_2\) and one mole of \(O_2\) on the reactant side and two moles of \(SO_3\) on the product side. As a result, the forward reaction leads to a decrease in the number of moles of gas, and according to Avogadro's principle, this corresponds to a decrease in volume. Therefore, Statement (3) is incorrect.

(4) The forward reaction leads to a decrease in volume:
This statement is correct based on the explanation provided above.

Conclusion:
The incorrect statement is (3) "The forward reaction leads to an increase in volume."