(a)[2]
Describe how universal indicator paper is used to find the water’s pH value.
(b(i))[2]
Air is forced through the aeration tank. Name the two gases that form most of the air.
(b(ii))[2]
Explain how the filter helps purify the water.
(b(iii))[1]
Explain why chlorine is used in water treatment.
(c)[2]
State the change in colour for this test.