## Question 1

Potassium is a metal above magnesium in the reactivity series. How would you expect it to react with (a) oxygen (b) water?

## Solution 1

(a) Reacts vigorously with oxygen
(b) Reacts vigorously with water

## Question 2

A metal does not react with cold water but it reacts slowly with dilute hydrochloric acid. Would it be placed above or below zinc in the reactivity series?

## Solution 2

Below zinc
Zinc reacts quickly with with hydrochloric acid. So if a metal reacts slowly with hydrochloric acid, that metal is less reactive than zinc and it goes below zinc on the reactivity series.

## Question 3

Here are some facts about a metal X.
i) When heated strongly X reacts slowly with air to form an oxide coat.
ii) It does not react with dilute hydrochloric acid.
iii) It reacts slowly with steam to form an oxide.

Say whether you think that X is more reactive or less reactive than a) copper b) iron. Given reasons for your answers.

## Solution 3

a) X is more reactive than copper because X reacts with steam and copper does not.
b) X is less reactive than iron because iron reacts with dilute hydrochloric acid and X does not.

## Question 4

Place the metals X,Y and Z in order of decreasing reactivity. Identify the metals and write word equations to show the reactions occurring.

X – reacts slowly with cold water but more vigorously with steam to give a white oxide.
Y – reacts with steam to give an oxide that is yellow when hot and white when cold. It reacts with dilute acid to give a gentle evolution of hydrogen.
Z – reacts with cold water to give a gentle evolution of hydrogen.

## Solution 4

Looking at the properties of the metals, you can see that metal Z is the most reactive since it reacts gently with cold water. Y is the least reactive because it reacts with steam and not with cold water.

• Z
• X
• Y

Z is calcium because calcium reacts gently with cold water.
X is magnesium because magnesium reacts slowly with cold water but more vigorously with steam.
Y is zinc because zinc oxide is yellow when hot and white when cold.

calcium + water → calcium hydroxide + hydrogen
zinc + water (steam) → zinc oxide + hydrogen
zinc + hydrochloric acid → zinc chloride + hydrogen
magnesium + water → magnesium oxide + hydrogen

## Question 4

The table shows some properties of two elements A and B.

Element AElement B
Appearanceshiny solidblack solid
Melting point600°C80°C
Tensile strength
Electrical Conductivity
Result on hitting with a hammer

a) Complete the table.
b) Say which element is metallic.
c) Which element would be used to insulate an electrical wire?
d) Which element would make the strongest cable to hold a large weight?

## Solution 4

Element AElement B
Appearanceshiny solidblack solid
Melting point600°C80°C
Tensile strengthHighLow
Electrical ConductivityGoodPoor
Result on hitting with a hammerflattens into a sheetbreaks

b) Element A
c) Element B
d) Element A

#### Juliet Muturuki

Quantity Surveyor and Freelance Writer.

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