Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 20257 AprilMorning Shift
Exam
JEE Main
Year
2025
Date
7 April
Shift
Morning Shift
Subject
Chemistry
Chapter
Chemical Kinetics

JEE Main 2025 · 7 April · Morning Shift · Chemistry · Chemical Kinetics

Reaction A(g) arrow 2 ~B(~g)+C(g) is a first order reaction. It was...

Reaction A(g)→2 B( g)+C(g)\mathrm{A}(\mathrm{g}) \rightarrow 2 \mathrm{~B}(\mathrm{~g})+\mathrm{C}(\mathrm{g}) is a first order reaction. It was started with pure A
Reaction A(g) arrow 2 ~B(~g)+C(g) is a first order reaction. It was started with pure A Which of the following option
Which of the following option is incorrect?

Options

  1. AInitial pressure of A is 80 mm Hg
  2. BThe reaction never goes to completion
  3. CRate constant of the reaction is 1.693 min−11.693 \mathrm{~min}^{-1}
  4. DPartial pressure of A after 10 minute is 40 mm Hg

Correct answer

C. Rate constant of the reaction is 1.693 min−11.693 \mathrm{~min}^{-1}

Step-by-step solution

A(g)⟶2 B( g)+C(g)\mathrm{A}(\mathrm{g}) \longrightarrow 2 \mathrm{~B}(\mathrm{~g})+\mathrm{C}(\mathrm{g})
t=0P0t→∞02P0P0\begin{array}{llll}\mathrm{t}=0 & \mathrm{P}_0 & & \\ \mathrm{t} \rightarrow \infty & 0 & 2 \mathrm{P}_0 & \mathrm{P}_0\end{array}
P∞=3P0=240P0=80 mm of Hg\begin{aligned} \mathrm{P}_{\infty}=3 \mathrm{P}_0 & =240 \\ \mathrm{P}_0 & =80 \mathrm{~mm} \text{ of } \mathrm{Hg}\end{aligned}
Kt=ln⁡(P∞−P0P∞−Pt)\mathrm{Kt}=\ln \left(\frac{\mathrm{P}_{\infty}-\mathrm{P}_0}{\mathrm{P}_{\infty}-\mathrm{Pt}}\right)
K×10=ln⁡(240−80240−160)K \times 10=\ln \left(\frac{240-80}{240-160}\right)
K=ℓn210=0.0693 min−1\mathrm{K}=\frac{\ell \mathrm{n} 2}{10}=0.0693 \mathrm{~min}^{-1}
Option (3) is incorrect
Practice Chemical Kinetics on Quantrex Academy →

More from Chemical Kinetics

For a reversible reaction R leftharpoons P , at constant temperature, both the forward… JEE Advanced 2026For a first-order reaction R P at a given temperature, k is the rate constant. For this… JEE Advanced 2026Given below are two statements: R=8.314 J K ^ -1 mol ^ -1 and 1 cal =4.2 J Statement I… JEE Main 2026Decomposition of a hydrocarbon follows the equation k = (5.5 × 10^ 11 \,s^ -1 )\,e^… JEE Main 2026For a reaction A arrow P at T K , the half life (t_ 1/2 ) is plotted as a function of… JEE Main 2026First order gas phase reaction A arrow B + C p_i = initial pressure of gas A, p_t = total… JEE Main 2026If the half life of a first order reaction is 6.93 minutes then the time required for… JEE Main 2026Consider the given graph showing variation of reactant concentration with time. Three… JEE Main 2026 Full Chemical Kinetics list All JEE Main PYQs