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Chemistry · PYQ NEET UG 2016(1)
हिन्दीLithium has a bcc structure. Its density is \( 530 \text{ kg m}^{-3} \) and its atomic mass is \( 6.94 \text{ g mol}^{-1} \). Calculate the edge length of a unit cell of lithium metal. \( (N_0 = 6.02 \times 10^{23} \text{ mol}^{-1}) \)
Correct answer · Option 2
\( 352 \text{ pm} \)
Explanation
Using \( d = \frac{Z \cdot M}{N_A \cdot a^3} \) for bcc \( (Z=2) \), \( a^3 = \frac{2 \times 6.94 \times 10^{-3}}{6.02 \times 10^{23} \times 530} = 4.34 \times 10^{-29} \text{ m}^3 \), giving \( a \approx 352 \text{ pm} \).
