JEE Main · 2026 · 22 Jan 2026 · Shift 2 · Some Basic Concepts of Chemistry

A + 2 B ⟶ AB_{2}

36.0 g of 'A' (Molar mass :

60 g mol^{- 1}

) and 56.0 g of ' B ' (Molar mass :

80 g mol^{- 1}

) are allowed to react. Which of the following statements are correct?
(A) ' A ' is the limting reagent
(B) 77.0 g of

AB_{2}

is formed
(C) Molar mass of

A B_{2}

140 g mol^{- 1}

(D) 15.0 g of A is left unreacted after the completion of reaction.

Choose the correct answer from the options given below :

Answer: (C)

Solution

The amounts taken are

\frac{36.0}{60} = 0.60

mol of A and

\frac{56.0}{80} = 0.70

mol of B. Since

A + 2B \to A B_{2}

needs

1.20

mol of B for

0.60

mol of A, B is the limiting reagent, so A is not limiting and statement (A) is wrong. The

0.70

mol of B consumes

0.35

mol of A to give

0.35

mol of

A B_{2}

, whose molar mass is

60 + 2 \times 80 = 220 g mo l^{- 1}

, so statement (C) is wrong. The

A B_{2}

formed weighs

0.35 \times 220 = 77.0

g and the A left over is

(0.60 - 0.35) \times 60 = 15.0

g, so statements (B) and (D) are correct. The correct statements are B and D only.

JEE Main · 2026 · 22 Jan 2026 · Shift 2 · Single correct option