Find: (a) the total number of protons (b) the total mass of protons in 34 mg of NH3 at STP. Will the answer change if the temperature and pressure are changed?

(a) Number of protons present in 1 molecule of ammonia = 7 + 3 = 10.
Number of molecules present in 34 mg of ammonia is 6.023 × 10²³ × (34 × 10⁻³ g) / (17 g/mol) = 1.2044 × 10²¹.
Total number of protons present in 34 mg of ammonia = 10 × 1.2044 × 10²¹ = 1.2044 × 10²²
(b) Total mass of protons present in 34 mg of ammonia at STP is: 1.6726 × 10⁻²⁷ kg × 1.204 × 10²² = 2.0138 × 10⁻⁵ kg.
When temperature and pressure are changed, there is no difference in the answer.