Question

Consider the following conventions related to thermochemical equations.
I. The coefficients of different substances in a balanced thermochemical equation show only number of moles involved in the reaction.
II. Enthalpy is an extensive property thus if a thermochemical equation is multiplied or divided by an integer $n$, the value of ${\Delta }_r{H}^{\circ }$ is also multiplied or divided by the integer, $n$.
III. On reversed a reaction, the sign of $\Delta H$ is also reversed but its magnitude also changes.
Select the correct statement and choose the correct option.

• A. Only $I$
• B. Only $III$
• C. Both $I$ and $II$
• D. All of these

Answer 1

Answer: (C)

Statement I and II are correct, while the statement III is incorrect.
It's correct form is as follows :
"On reversing a reaction, the sign of $\Delta H$ is also reversed but its magnitude remains the same.