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Chemistry · Some Basic Concepts of Chemistry (Mole Concept) + Stoichiometry

JEE Main 2026 — 22 January, Evening Shift — Question 48

For the reaction, A+2B→AB2\mathrm{A + 2B \rightarrow AB_2}. 36.0 g36.0\,\mathrm{g} of A\mathrm{A} (molar mass =60 g mol−1=60\,\mathrm{g\,mol^{-1}}) and 56.0 g56.0\,\mathrm{g} of B\mathrm{B} (molar mass =80 g mol−1=80\,\mathrm{g\,mol^{-1}}) are allowed to react.

Which of the following statements are correct?

(A) A\mathrm{A} is the limiting reagent (B) 77.0 g77.0\,\mathrm{g} of AB2\mathrm{AB_2} is formed (C) Molar mass of AB2\mathrm{AB_2} is 140 g mol−1140\,\mathrm{g\,mol^{-1}} (D) 15.0 g15.0\,\mathrm{g} of A\mathrm{A} is left unreacted

Choose the correct answer from the options given below:

  1. Option A:

    C and D only

  2. Option B:

    A and C only

  3. Option C:

    B and D only

    Correct
  4. Option D:

    A and B only

Answer: C

Step-by-step solution

Given reaction: A+2B→AB2\mathrm{A + 2B \rightarrow AB_2}

Moles of A\mathrm{A} =36.060=0.6 mol= \frac{36.0}{60} = 0.6\,\mathrm{mol}

Moles of B\mathrm{B} =56.080=0.7 mol= \frac{56.0}{80} = 0.7\,\mathrm{mol}

Stoichiometry, 1 A:2 B1\,\mathrm{A} : 2\,\mathrm{B}

For 0.6 mol0.6\,\mathrm{mol} A, required B = 1.2 mol1.2\,\mathrm{mol} Available B = 0.7 mol0.7\,\mathrm{mol}

Hence, B\mathrm{B} is the limiting reagent.

A consumed =0.72=0.35 mol= \frac{0.7}{2} = 0.35\,\mathrm{mol}

A left =0.6−0.35=0.25 mol= 0.6 - 0.35 = 0.25\,\mathrm{mol}

Mass of A left =0.25×60=15.0 g= 0.25 \times 60 = 15.0\,\mathrm{g}

Molar mass of AB2\mathrm{AB_2} =60+2×80=220 g mol−1= 60 + 2 \times 80 = 220\,\mathrm{g\,mol^{-1}}

Moles of AB2\mathrm{AB_2} formed =0.35 mol= 0.35\,\mathrm{mol}

Mass of AB2\mathrm{AB_2} formed =0.35×220=77.0 g= 0.35 \times 220 = 77.0\,\mathrm{g}

Thus statements (B) and (D) are correct.

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Paper
22 January, Evening Shift
Subject
Chemistry
Chapter
Some Basic Concepts of Chemistry (Mole Concept) + Stoichiometry
Topic
Chemical Equations, Stoichiometry and Limiting Reagent
For the reaction, A + 2B rightarrow AB 2 . 36.0\, g of A (molar mass… | JEE Main 2026 PYQ with Solution · DhiX AI