Initially, 2 moles of compound $P$ were introduced into a vessel. On heating, some of compound $P$ decomposed, and a dynamic equilibrium was set up among chemicals $P$, $Q$ and $R$. When equilibrium was reached, $x$ mol of $R$ were present and the total amount of substance present was $(2 + x)$. What is the equation for this equilibrium?
- A$P \rightleftharpoons 2Q + R$
- B$2P \rightleftharpoons 2Q + R$
- C$2P \rightleftharpoons Q + R$
- D$2P \rightleftharpoons Q + 2R$