The equation $\frac{1}{2} H_2 + \frac{1}{2} Cl_2 \to HCl$ $(\Delta H_{298} = -22.060 \ kcal)$ means:

• A
  The heat absorbed when one gram molecule of $HCl$ is formed from its elements at $25 \ ^oC$ is $22.060 \ kcal$.
• B
  The heat evolved when one gram molecule of $HCl$ is formed from its elements at $298 \ K$ is $22.060 \ kcal$.
• C
  The heat absorbed when one atom of hydrogen reacts with one atom of chlorine to form one molecule of $HCl$ at $25 \ ^oC$ and $1 \ atm$ pressure is $22.060 \ kcal$.
• D
  The heat absorbed when one gram equivalent of $HCl$ is formed from its elements at $298 \ K$ is $22.060 \ kcal$.