1. 1/12 2. 1/2 3. 1/3 4. 1/4

Topic: Ionic bonding and lattice enthalpy· Chemical Bonding and Molecular Structure

What fraction of one edge centred octahedral void lies in one unit cell of fcc?

1. \(\dfrac{1}{12}\)

2. \(\dfrac{1}{2}\)

3. \(\dfrac{1}{3}\)

4. \(\dfrac{1}{4}\)

Doubtly Asked 30 Oct 2026 NEET UG 2023 neet Save WhatsApp Report

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Answer: 4. \(\dfrac{1}{4}\)

Key idea: An octahedral void at an edge centre is shared by the 4 unit cells meeting at that edge.

An fcc cell has one octahedral void at the body centre and others at the 12 edge centres. Each edge-centre void contributes \(\frac14\) to one unit cell (12 x 1/4 = 3, plus 1 at body centre = 4 in all).

Fraction = 1/4. Option 4.

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

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What fraction of one edge centred octahedral void lies in one unit cell of fcc?

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