Question

Gold crystallizes in face centred cubic structure. If atomic mass of gold is 197 g mol^-1, the mass of unit cell of gold is ______.

Options

• 6.5 × 10^-23 kg

• 3.25 × 10^-23 kg

• 1.3 × 10^-24 kg

• 3.9 × 10^-24 kg

Answer 1

Gold crystallizes in face centred cubic structure. If atomic mass of gold is 197 g mol^-1, the mass of unit cell of gold is 1.3 × 10^-24 kg.

Explanation:

Since, 197 g of gold = 6.022 × 10²³ particles

∴ x g of FCC crystal of gold = 4 particles

∴ x = `(197 xx 4)/(6.022 xx 10^23)`

= 130.8 × 10^-23 g

= 0.1308 × 10^-23 kg

= 1.3 × 10^-24 kg