Question

18. Calculate the number of gold atoms in 0.3 g of 20 carat gold. The 24 carat gold is taken as 100%
pure gold. Atomic mass of gold = 197 u.
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Answer 1

Answer:

300mgof a gold ring is 20 of 20 Carat . It means in 300 mg ring , 20 part is pure gold and 4 part is other metal.

∴ weight of pure gold in 300mg =300 × (20/24) × 100 = 250mg

➜Now, weight of pure gold = 250mg = 0.25g

molecular weight of pure gold = 197g/mole

━☞∴ mole = weight of gold/molecular weight

of gold

= 0.25/197

Now, number of gold atoms = number of mole of gold × 6.023 × 10²³

= 0.25/197 × 6.023 × 10²³

= 7.64 × 10²⁰

Answer 2

Answer:

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