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Copper exhibits a face-centered cubic (fcc) arrangement. If the atomic radius of copper is 128 pm, what is the length of the unit cell edge?

1. 36.2 pm
2. 362 nm
3. 3.62 × 10^−10 cm
4. 362 × 10^−10 cm

Correct answer: 362 × 10^−10 cm

Solution

For fcc, a=2*sqrt(2)*r=2*1.4142*128=362 pm=3.62e-8 cm. Option '362 x 10^-10 cm' equals 3.62e-8 cm, which is correct. Stored '3.62 x 10^-10 cm' is 100x too small and wrong.

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