CAIE IGCSE Chemistry Aqueous Cation Tests

Cambridge IGCSE Chemistry 0620 syllabus for exams in 2026, 2027 and 20282026–2028

Practise identifying aqueous cations from precipitate colours, solubility in excess reagent and the ammonia released by an ammonium salt.

How this is tested

add sodium hydroxide or aqueous ammonia and record the precipitate colour for the named cation
use solubility in excess reagent to distinguish ions such as aluminium, zinc and copper
identify ammonium ions by warming with sodium hydroxide and testing the released ammonia gas

[Maximum number: 1]

A substance is tested with three different reagents.
Which row shows the results obtained with aqueous iron(II) nitrate?

aqueous
sodium hydroxide

acidified aqueous
silver nitrate

acidified aqueous
barium nitrate

green precipitate,
insoluble in excess

no reaction

green precipitate,
insoluble in excess

white precipitate

white precipitate,
insoluble in excess

cream precipitate

no reaction

white precipitate that
dissolves in excess

no reaction

white precipitate