The number of molecules in 0.25 mole of ammonia

[LokeshCBSE]

Calculate

1. the mass of 1.0505 x 10²³ molecules of carbon dioxide (CO₂).
   [Molar mass of CO₂ = 44 g]
2. the number of molecules in 0.25 mole of ammonia (NH₃).
3. the formula unit mass of Na₂SO₃.
   [Atomic mass of Na = 23 u, S = 32 u, O = 16 u, H = lu, N_A = 6.022 x 10²³ mol ^–1]

[LokeshCBSE]

1. Mass of 1.0505 x 10²³ molecules of CO₂
2. ∵ 1 mole of NH₃ have molecule = 6.022 x 10²³ x 0.25
   = 1.5055 x 10²³ molecules
3. Formula unit mass of Na₂SO₃ = 2 x 23 + 32 + 3 x 16
   = 46 + 32 + 48 = 126 amu