Question

Which of the following salt in dry heating test turn pink on cooling and blue on heating?

• A. $F{e}^{2+}$
• B. $C{u}^{2+}$
• C. $C{o}^{2+}$
• D. $Z{n}^{2+}$

Answer 1

The correct option is C $C{o}^{2+}$

$0.1g$ of the dry salt is a taken in a clean and dry test tube and heated for about one minute and observe the colour of the residue when it is hot and also when it becomes cold.