The diameter of the zinc atom is 2.6 Å. Calculate (a) radius of zinc atom in pm and (b) the number of atoms present in a length of 1.6 cm if the zinc atoms are arranged side by side lengthwise.

(i)The diameter of zinc atom is 2.6 Å = 2.6 × 10⁻¹⁰ m.
The radius of Zn atom is 2.6 × 10⁻¹⁰ / 2 = 1.3 × 10⁻¹⁰ m = 130 × 10⁻¹² m = 130 pm
(ii) The number of Zn atoms present in 1.6 cm of length are 1.6 cm / (2.6 × 10⁻⁸ cm) = 6.154 × 10⁷.