Hydrogen and oxygen combine in the ratio of 1 : 8 by mass to from water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?

(a) Calculate the number of moles in 112 g of iron.

(b) Calculate the mass of 0.5 mole of sugar (C₁₂H₂₂O₁₁).

[Atomic mass of Fe = 56 u, C = 12 u, H = 1 u, O = 16 u]

Calculate the mass of 3.011 × 10²³ atoms of nitrogen.

(a) Define the term ‘molecular mass’.

(b) Determine the molecular mass of ZnSO₄.

[Atomic mass of Zn = 65 u, S = 32 u, O = 16 u]

Calculate:

(a) The number of moles of Sulphur (S₈) present in 16 g of solid sulphur.

(b) the mass of 10 moles of sodium sulphite (Na₂SO₃).

(c) the number of atoms in 11.5 g of Na.

[atomic mass: Na = 23u; S = 32u, O = 16u, N_A = 6.022 × 10²³ mol^–1]

Calculate the mass of 6.022 × 10²³ N₂ molecules.

In photosynthesis, 6 molecules of carbon dioxide combine with an equal number of water molecules through a complex series of reactions to give a molecule of glucose having a molecular formula C₆ H₁₂ O₆. How many grams of water would be required to produce 18 g of glucose? Compute the volume of water so consumed assuming the density of water to be 1 g cm^–3.

How many grams of magnesium will have the same number of atoms as 6 grams of carbon? (Mg = 24 u; C = 12 u)

The mass of one atom of an element X is 2.0 × 10^-23 g.

(i) Calculate the atomic mass of element X.

(ii) What could element X be?

Calculate the mass of each of the following:

10 moles of hydrogen cyanide