The general gas equation may be applied to determine the $M_r$ of a gas. For a gas sample with mass $m\ \text{g}$, which expression gives the value of $M_r$?
- A$M_r = \frac{mpV}{RT}$
- B$M_r = \frac{pVRT}{m}$
- C$M_r = \frac{mRT}{pV}$
- D$M_r = \frac{pV}{mRT}$