Grade 10 A and B

. A student measures 25.00 cm³ of dilute hydrochloric acid accurately. Which apparatus is most suitable?

• beaker

• measuring cylinder

• burette

• dropping pipette

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.

Calcium metal reacts with water to form a solution of calcium hydroxide and hydrogen gas.

Which equation is correct?

• Ca(s) + H₂O(aq) ==> CaOH(aq) + H(g)

• Ca(s) + 2H₂O(aq)==>Ca(OH)₂(s) + 2H₂(g)

• Ca(s) + 2H₂O(l)==> Ca(OH)₂(aq) + H₂(g)

• Ca(s) + H₂O(l)==>CaOH(l) + H(g)

Which change in reaction conditions increases both the collision rate and the proportion of molecules with sufficient energy to react?

• addition of a catalyst

• increasing the concentration of a reactant

• increasing the surface area of a reactant

• increasing the temperature of the reaction

When blue-green crystals of nickel(II) sulfate are heated, water is produced and a yellow solid remains. When water is added to the yellow solid, the blue-green colour returns.

Which process describes these changes?

• combustion

• corrosion

• neutralisation

• reversible reaction

Which property of aluminium makes it useful in the manufacture of aircraft?

• conducts electricity

• high boiling point

• low density

• silver colour

The exhaust gases from cars contain oxides of nitrogen.

How are these oxides of nitrogen formed?

• N₂ and O₂ from the air react together at the high temperatures in the engine.

• N₂ and O₂ from the petrol react together in the car exhaust.

• N₂ from the petrol reacts with O₂ at the high temperatures in the engine.

• N₂ reacts with O₂ from the air in the catalytic converter.

In the manufacture of aluminium by electrolysis, aluminium oxide is dissolved in molten cryolite.

Why is cryolite used?

• It lowers the melting point of the aluminium.

• It makes the aluminium a better conductor.

• It removes impurities from the aluminium.

• The mixture has a lower melting point than pure aluminium oxide.

Which statement about a fuel cell in a car is correct?

• The fuel cell produces heat, which powers the car.

• The fuel cell is supplied with hydrogen directly from the air.

• The only emission from a fuel cell is nitrogen gas, which is non-polluting.

• The fuel cell produces electricity, which powers an electric motor.