Question

A gaseous reaction \(X_2(g) \rightarrow Y + \frac{1}{2}Z(g)\). There is an increase in pressure from 100 mm to 120 mm in 5 minutes. The rate of disappearance of \(X_2\) is:

• A. \(8\,\text{mm min}^{-1}\)
• B. \(2\,\text{mm min}^{-1}\)
• C. \(16\,\text{mm min}^{-1}\)
• D. \(4\,\text{mm min}^{-1}\)

Hint:

For gas reactions, pressure change is proportional to change in moles.

Answer 1

The Correct Option is D

Step 1: Pressure increase \(=20\,\text{mm}\) in \(5\,\text{min}\).
Step 2: \[ \text{Rate of increase} = 4\,\text{mm min}^{-1} \]
Step 3: From stoichiometry, disappearance rate of \(X_2\) equals pressure increase rate.