Question

The unit of molar gas constant is :

• A. $J{K}^{-1}mo{l}^{-1}$
• B. $J$
• C. $JK$
• D. $Jmo{l}^{-1}$

Answer 1

Answer: (A)

From ideal gas equation $PV=\mu RT$
$\Rightarrow R=\frac{PV}{\mu T}$
$\therefore$ Unit of $R=\frac{\text{ Unit pressure }\times \text{ unit of volume }}{\text{ mol }\times \text{ unit of temperature }}$
$=\frac{{\text{ newton-metre }}^{-2}\times {\text{ metre }}^3}{\text{ mol }-K}$
$=\frac{\text{ newton-metre }}{\text{ mol-K }}$
$=\frac{\text{ joule }}{\text{ mol-K }}$
$=\left(J-mo{l}^{-1}{K}^{-1}\right)$