mole and formulae

Diagram shows a box of aspirin which can relieve fever and pain. If the molecular formula of aspirin is C₉H_XO₄, determine the value of x.

Which of the following gases contains 0.4 mol of atoms at room temperature and pressure?

[1 mol of gas occupies the volume of 24 dm³ at room temperature and pressure]

• 4.8 dm³ He

• 4.8 dm³ H₂

• 4.8 dm³ SO₃

• 4.8 dm³ CO₂

A compound with formula XCO₃ has a relative formula mass of 125. What is the relative atomic mass of X? [Ar C = 12 and O = 16]

• 24

• 40

• 59

• 65

Calculate the volume of carbon dioxide gas produced for a complete combustion of 30 g of ethane gas at STP. [Ar H = 1, C = 12, 1 molar volume 22.4 dm³ mol^-1 at STP]

• 22.4 dm³

• 44.8 dm³

• 67.2 dm³

• 89.6 dm³

What is the molecular formula if the empirical formula is CH₂O and the molecular molar mass is 180?

• CH₂O

• C₂H₄O₂

• C₄H₈O₄

• C₆H₁₂O₆

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

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

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

Calculate the relative molecular mass of H₂SO₄.