$\begin{aligned}
& \text { rate }=\mathrm{k}_2[\mathrm{A}]\left[\mathrm{B}_2\right] \ldots \ldots \
& \left(\frac{\mathrm{k}1}{\mathrm{k}{-1}}\right)=\left(\frac{[\mathrm{A}]^2}{\left[\mathrm{A}_2\right]}\right) \
& \Rightarrow[\mathrm{A}]=\sqrt{\frac{\mathrm{k}1}{\mathrm{k}{-1}}} \cdot \sqrt{\left[\mathrm{A}_2\right]}
\end{aligned}Substitutingin(1);weget\begin{aligned} & \text { Rate }=\mathrm{k}_2 \sqrt{\frac{\mathrm{k}1}{\mathrm{k}{-1}}} \cdot\left[\mathrm{A}_2\right]^{\frac{1}{2}} \cdot\left[\mathrm{~B}_2\right] \ & \therefore \text { order }=\left(\frac{3}{2}\right)=1.5\end{aligned}$
JEE Main 2025 — Chemistry Physical Chemistry
2025mcqhard
The reaction A2+B2→2AB follows the mechanism 
The overall order of the reaction is :
Official previous-year question
Held on 29 Jan 2025 · Verified 6 Jul 2026.
Options
- A
2
- B
2.5
- C
3
- D
1.5
Did you get this right?
Sign in to track your attempts and accuracy.
Your note
Sign in to keep a private note on this question. Nothing you write is ever public.
JEE Main Physical Chemistry in other years
More JEE Main Physical Chemistry questions
The ratio of mass percentage (w/w) of C : H in a hydrocarbon is $12 : 1$. It has two carbon atoms. The weight (in g) of $CO_2(g)$ formed when $3.38$ g of this hydrocarbon is completely burnt in oxygen is : (Given : Molar mass in g mol$^{-1}$ C : 12, H : 1, O : 16)
2026medium
The correct order of total number of atoms present in<br>(A) $2$ moles of cyclohexane<br>(B) $684$ g of sucrose<br>(C) $90.8$ L of dihydrogen at STP<br>is:
2026medium
An oxide of iron contains $69.9\%$ iron, its empirical formula, is: (Given: Molar mass of Fe and O are $56$ and $16$ g mol$^{-1}$ respectively.)
2026easy
What volume of hydrogen gas at STP would be liberated by action of $50\text{ mL}$ of $H_2SO_4$ of $50\%$ purity (density $= 1.3\text{ g mL}^{-1}$) on $20\text{ g}$ of zinc ?<br>Given : Molar mass of H, O, S, Zn are $1, 16, 32, 65\text{ g mol}^{-1}$ respectively.
2026medium
For the given reaction:<br>$\mathrm{CaCO}_{3}+2 \mathrm{HCl} \longrightarrow \mathrm{CaCl}_{2}+\mathrm{H}_{2} \mathrm{O}+\mathrm{CO}_{2}$<br>If $90 \mathrm{~g} \mathrm{CaCO}_{3}$ is added to 300 mL of HCl which contains $38.55 \% \mathrm{HCl}$ by mass and has density $1.13 \mathrm{~g} \mathrm{~mL}^{-1}$, then which of the following option is correct ?<br>Given molar mass of $\mathrm{H}, \mathrm{Cl}, \mathrm{Ca}$ and O are 1, 35.5, 40 and $16 \mathrm{~g} \mathrm{~mol}^{-1}$ respectively.
2026medium
Other Chemistry topics for JEE Main
Keep practicing Physical Chemistry
Work through every JEE Main Physical Chemistry PYQ, year by year.