JEE Main 2026 Apr 6 Shift 1, Chemistry Q1: Mole Concept And Equivalent Concept

JEE Main2026Apr 6, Shift 1Chemistry

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.)

Solution

Mass of Fe in $100$ g sample $= 69.9$ g; mass of O $= 30.1$ g.

Moles: Fe $= \frac{69.9}{56} \approx 1.248$ ; O $= \frac{30.1}{16} \approx 1.881$ .

Mole ratio Fe : O $= 1 : 1.507 \approx 2 : 3$ .

$∴$ Empirical formula is $Fe_{2} O_{3}$ .

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