Which statement explains why ammonia gas, NH₃, diffuses at a faster rate than

hydrogen chloride gas, HCl ?

• Ammonia expands to occupy all of the space available.

• Ammonia has a smaller relative molecular mass than hydrogen chloride.

• Ammonia is an alkali and hydrogen chloride is an acid.

• Ammonia molecules diffuse in all directions at the same time.

2.00 g of powdered calcium carbonate is added to 50.0 cm³ of hydrochloric acid.

Which apparatus is used to measure the calcium carbonate and the hydrochloric acid?

• calcium carbonate- balance; hydrochloric acid-burette

• calcium carbonate-balance; hydrochloric acid-thermometer

• calcium carbonate-pipette; hydrochloric acid-burette

• calcium carbonate-pipette; hydrochloric acid-thermometer

The measurements from a chromatography experiment using substance F are shown. The diagram is not drawn to scale.

What is the R_f value of F?

• 0.55

• 0.61

• 0.90

• 1.64

Which statement describes the structure of an ionic compound?

• It is a giant lattice of oppositely charged ions.

• It is a giant lattice of positive ions in a ‘sea’ of electrons.

• It is a giant molecule of oppositely charged ions.

• It is a simple molecule of oppositely charged ions.

Propane burns in oxygen.

C₃H₈ + xO₂ → 3CO₂ + yH₂O

Which values of x and y balance the equation?

• x:5, y:4

• x:7, y:4

• x:10, y:8

• x:13, y:8

Magnesium reacts with sulfuric acid.

What are the formulae of the products formed in this reaction?

• MgSO₄ and H₂

• MgSO₄ and H₂O

• Mg(SO₄)₂ and H₂

• Mg(SO₄)₂ and H₂O

Which statement explains why graphite is used as a lubricant?

• All bonds between the atoms are weak.

• It conducts electricity.

• It has a low melting point.

• Layers in the structure can slide over each other.

Ethanol is used as a fuel.

ethanol + oxygen --> carbon dioxide + water

Which statements are correct?

1 The reaction is endothermic.

2 The products have more energy than the reactants.

3 The oxygen for this reaction comes from the air.

4 The temperature of the reaction mixture rises during this reaction.

• 1 and 2

• 1 and 3

• 2 and 4

• 3 and 4

Which metal has variable oxidation states?

• aluminium

• calcium

• copper

• sodium

What is the catalyst in the Haber process?

• Fe

• Ni

• Pt

• V₂O₅