When iron fillings are added to aqueous copper (II) sulphate solution a reaction takes place. State three observations made during the reaction.

Here are the answers to the questions:

26.
Three observations made during the reaction are:

• The blue colour of the copper (II) sulphate solution fades or turns green.
• A reddish-brown solid (copper) is deposited.
• The iron fillings decrease in size or disappear.

27.

i) Chemical test:

• Add anhydrous copper (II) sulphate. If water is present, it will turn from white to blue.

ii) Physical test:

• Determine its boiling point. Pure water boils at $\boxed{\text{100}^\circ\text{C}}$ at standard atmospheric pressure.

28.

a) Select elements found in;

i) the same group:

• W and U (Both are in Group 2, having 2 valence electrons).

ii) period three:

• X, U, and Y (All have 3 electron shells).

b) What is the family name given the group members to which element Y belongs:

• Halogens (Element Y has 7 valence electrons, placing it in Group 17).