A 5.0 g sample of an element (M=40 g mol^-1) has a bcc structure. Use N_A = 6.022x10^23 mol^-1. The number of unit cells in the sample is xx10^22. Find x (two decimals).

JEE Main levelNumerical answerDifficulty 2 of 3ss155

A $5.0 g$ sample of an element ( $M = 40 g mo l^{- 1}$ ) has a bcc structure. Use $N_{A} = 6.022 \times 1 0^{23} mo l^{- 1}$ . The number of unit cells in the sample is $x \times 1 0^{22}$ . Find $x$ (two decimals).

Numerical answer type, tolerance 0.02.

Moles

= 5.0/40 = 0.125

; atoms

= 0.125 \times 6.022 \times 1 0^{23} = 7.5275 \times 1 0^{22}

. A bcc cell has

Z = 2

, so unit cells

= 7.5275 \times 1 0^{22} /2 = 3.76 \times 1 0^{22}