On strongly heating

CHEMISTRY · Single correct · GCSE · Chemistry · Chemical Analysis · Chemical Analysis

Problem

On strongly heating, a blue salt leaves a black residue. Which of the following cations can be present in the salt? (1)

\text{Fe}^{2+}

(2)

\text{Fe}^{3+}

(3)

\text{Cu}^{2+}

(4)

\text{Zn}^{2+}