Did you read over the notes on 'Qualitative Analysis'

If a white precipitate forms, which is insoluble in excess sodium hydroxide, a Group II cation may be present.

When a white precipitate is formed that dissolves when excess sodium hydroxide is added to give a colourless solution. Identify the ions that may be present:

Identify the cation that gives a coloured precipitate of 'grey-green'

Identify the cation that gives a coloured precipitate of 'Pale blue'