Chemistry - Ideal Gas Question with Solution | TestHub

The ideal gas law, $PV=nRT$, relates pressure (P), volume (V), moles (n), and temperature (T). Since the container is rigid, volume (V) is constant. R is the gas constant.

Initial state: $P_1=n_{1}R{T}_1/V$. Let initial moles of NH₃ be 'a' and temperature be 'T'. So, $P_1=aRT/V$.

Final state: Temperature is doubled to $2T$. NH₃ completely dissociates: $2N{H}_3\to N_2+3H_2$.

From 'a' moles of NH₃, we get $a/2$ moles of N₂ and $3a/2$ moles of H₂.

Total moles $n_2=a/2+3a/2=4a/2=2a$.

So, $P_2=n_{2}R(2T)/V=(2a)R(2T)/V=4aRT/V$.

Ratio: $P_2/P_1=(4aRT/V)/(aRT/V)=4$.

The final answer is $\boxed{4}$.