The confirmatory test involves diazotization, followed by coupling with phenol to yield a red azo dye. Hence, the reagents used are:
A = NaNO2 + HCl, 0–5°C and B = phenol
\( \text{M} \xrightarrow{\text{CH}_3\text{MgBr}} \text{N} + \text{CH}_4 \uparrow \xrightarrow{\text{H}^+} \text{CH}_3\text{COCH}_2\text{COCH}_3 \)