Question

ANSWER.............................

Answer 1

one molecule of oxygen has two oxygen atoms.

we know that each oxygen atom has 8 protons and 8 neutrons

so the mass of one oxygen atom is (8u + 8u) = 16u where u is the unified mass.

so the mass of one oxygen molecule which contains two oxygen atoms is

= 16u + 16u = 32u

let us check the options which has the same mass as the one molecule of O₂

A) we know that one mole of He weighs 4 grams. this cannot be the answer because one mole of He itself weighs 4 grams where as the one molecule of oxygen weighs 32u = 32 × 1.67 × 10⁻²⁴grams

B) we know that one mole of H₂ weighs 2 grams. this cannot be the answer beacuse one mole of H₂ itself weighs 2 grams where as the one molecule of oxygen weighs 32u = 32 × 1.67 × 10⁻²⁴grams

C) we know that one molecule of CH₄ contains one Carbon atom and 4 hydrogen atoms. the mass of one carbon atom is (6 protons + 6 neutrons) = 12u and 4 hydrogen atoms each containing one proton weighs 4×1 = 4u. so the total mass of one molecule of CH₄ weighs 12u + 4u = 16u

⇒ two molecules of CH₄ weighs (16 × 2) = 32u which is equal to one molecule of oxygen.

so Option C is the answer