Mole Concept (use of 4 formulae)

The relative formula mass of a chloride, XCl, is 58.5. The relative atomic mass of X is .

• 11

• 17

• 23

• 35.5

Which of the following shows the correct steps for calculating the relative formula mass of CuSO₄.5H₂O?

• 64 + 32 + 16 + 1 + 16

• 64 + (1 × 32) + (4 × 16) + 5(2 + 16)

• 64 + (1 × 32) + (4 × 16) × 5(2 + 16)

• 4(64 + 32 + 16) + 5(2 + 16)

The mass of one mole of oxygen atoms is 16 g. What is the mass of one mole of oxygen gas?

• 8 g

• 16 g

• 24 g

• 32 g

What is the number of moles of hydrogen atoms in 1.7 g of ammonia gas (NH₃)?

• 0.1

• 0.3

• 1.4

• 1.7

10 g of magnesium oxide contains .

• 0.25 mol of magnesium oxide

• 0.5 mol of magnesium oxide

• the same number of moles as 10 g of zinc oxide

• 5 g of magnesium atoms and 5 g of oxygen atoms

Which of the following gases has the greatest mass at room temperature and pressure?

• 0.5 dm³ of argon (Ar)

• 200 cm³ of ammonia (NH₃)

• 5 dm³ of hydrogen (H₂)

• 1000 cm³ of water vapour (H₂O)

What is the number of oxygen molecules in 36 000 cm³ oxygen gas at room temperature and pressure?

• 3 × 10²³

• 9 × 10²³

• 1.2 × 10²⁴

• 2.4 × 10²⁴

Which of the following statements about the mole is incorrect?

• The mole is a unit of measurement for very small particles.

• A mole of any gas occupies 24 dm³ at room temperature and pressure.

• Equal volumes of any gas have the same mass.

• The mass of 1 mole of a compound is equal to its M_r in grams.

0.8 g of sodium hydroxide is dissolved to form a 250 cm³ aqueous solution. What is the concentration of this solution?

• 0.02 mol/dm³

• 0.08 mol/dm³

• 0.04 mol/dm³

• 0.80 mol/dm³

Which of the following solutions of hydrochloric acid has the highest concentration?

• 0.10 mol of HCl in 0.10 dm³ of solution

• 0.10 mol of HCl in 1.00 dm³ of solution

• 36.5 g of HCl in 0.10 dm³ of solution

• 36.5 g of HCl in 1.00 dm³ of solution