Suppose the elements X and Y combine to form two compounds XY_2 and X_3Y_2. When 0.1 mole of XY_2 weighs 10 g and 0.05 mole of X_3Y_2 weighs 9 g, the atomic weights of X and Y are

1. 60, 40

2. 20, 30

3. 30, 20

4. 40, 30

Doubtly Asked 30 Oct 2026 NEET UG 2016 Phase 2 Practice test neet Save WhatsApp Report

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Answer: 4. 40, 30

Key idea: molar mass = mass / moles, then form two equations in the atomic masses X and Y.

Subtracting: \(2X=80\Rightarrow X=40\). Then \(2Y=60\Rightarrow Y=30\).

Atomic weights are 40 and 30.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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