JEE Main 2023ChemistrySolid StateHardNumerical

JEE Main 2023 — Solid State Question with Solution

JEE Main 2023 (30 Jan Shift 2)

Question

Iron oxide FeO, crystallises in a cubic lattice with a unit cell edge length of 5.0Å. If density of the FeO in the crystal is 4.0 g cm-3, then the number of FeO units present per unit cell is _____ (Nearest integer)

Given : Molar mass of Fe and O is 56 and 16 g mol-1 respectively.
NA=6.0×1023 mol-1

Enter your answer

Show full solutionCorrect answer: 4
Correct answer
4

Step-by-step explanation

The density of the crystal can be calculated as follows,

d=Z×MN0×a3

d=densityZ=effective number of atomsM=Molar massN0=Avogadro's numbera=Edge length

4=Z×726×1023×125×10-24

Z=4.166≃4

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About this question

This is a previous-year question from JEE Main 2023, covering the Solid State chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.