Given that `K_c =` 13.7 at 546 K for `PCl_3(g) iff PCl_3(g) + Cl_2(g)`.
Calculate what pressure will develop in a 10-litre box at equilibrium at 546 K when 1 mole of `PCl_5` is introduced into the empty box.

Explanation

To solve the problem, we need to analyze the equilibrium reaction and apply the equilibrium constant expression. The reaction given is:

\[ PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2(g) \]

### Step 1: Set up the initial conditions
Initially, we have 1 mole of \( PCl_5 \) in a 10-liter box, and no \( PCl_3 \) or \( Cl_2 \) is present.

- Initial moles:
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