During the borax bead test, which metal cation produces a characteristic deep blue bead in both hot — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Cobalt ($Co^{2+}$) forms cobalt metaborate ($Co(BO_2)_2$), which is distinctly deep blue in both hot and cold conditions in the oxidizing flame. Copper is green when hot and blue when cold.