Question

How many atoms of carbon are present in a diamond weighing 0.5 carat? (one carat weighs 200 mg and assume diamond to be pure carbon)

(a) 5.02 x 10²¹

(b) 6 x 10²²

(c) 7 x 16¹⁹

(d) 8 x 10¹²

Answer 1

Correct option  (a) 5 x 10²¹

Explanation:

1 carat = 200 mg

0.5 carat = 100 mg

1 mole of C-atoms weighs = 12 g

⇒12 g of carbon = 6.023 x 10²³ C-atoms

⇒ 100 mg of carbon = (6.023 x 10²³ x 100)/12 x 1000

= 5.02 x 10²¹ atoms