JEE Main 2022 · 28 Jul · Shift 1 · Chemistry Q82

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ChemistryInteger+4 / -1Question 82 of 90

An element M crystallises in a body centred cubic unit cell with a cell edge of 300 pm. The density of the element is 6.0 g cm $^{-3}$ . The number of atoms present in 180 g of the element is ______ $\times10^{23}$ . (Nearest integer)

Your answer

Answer and worked solution

Official answer: 22

bcc ( $Z=2$ ). $M=\frac{\rho N_Aa^3}2=\frac{6\times6.022\times10^{23}\times2.7\times10^{-23}}2=48.8$ g mol $^{-1}$ .

Atoms $\frac{180}{48.8}\times6.022\times10^{23}=22.2\times10^{23}$ .

Answer: 22

Topics:Density of crystals Mole concept

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JEE Main 2022 · 28 Jul · Shift 1, Chemistry question 82