Properties of metals, alloys and reactivity — GCSE Chemistry practice questions

Question 1

The table gives some properties of four elements, W, X, Y and Z.

| element | melting point / °C | conducts electricity as a solid | when hit with a hammer |
|---|---|---|---|
| W | 113 | no | shatters |
| X | 1455 | yes | flattens |
| Y | 3652 | yes | crumbles |
| Z | 44 | no | crumbles |

Which element is a metal?

Accepted Answer

B: X. Metals conduct electricity as solids and are malleable, so they flatten instead of breaking when hammered. Only X does both. Y conducts but crumbles, as graphite does, so it is a non-metal.

Question 2

In which mixture do atoms of the solid metal lose electrons to the metal ions in the solution?

Accepted Answer

C: magnesium and aqueous silver nitrate. A displacement happens only when the solid metal is more reactive than the metal whose ions are in solution. Magnesium is above silver, so magnesium atoms lose electrons to silver ions: Mg + 2Ag⁺ → Mg²⁺ + 2Ag. In A, B and D the solid metal is less reactive than the metal in the solution, so nothing happens.

Question 3

Aluminium powder, with its oxide layer removed, reacts with aqueous copper(II) chloride.

Which is the ionic equation for this reaction?

Accepted Answer

B: 2Al + 3Cu²⁺ → 2Al³⁺ + 3Cu. Aluminium atoms become Al³⁺ ions and Cu²⁺ ions become copper atoms; the chloride ions are spectators and are left out. Two Al³⁺ (6+) balance three Cu²⁺ (6+), giving 2Al + 3Cu²⁺ → 2Al³⁺ + 3Cu.