323910 \[{\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}}\xrightarrow[{\left( {{\text{Step}}{\mkern 1mu} {\text{ - }}{\mkern 1mu} {\text{1}}} \right)}]{{{\text{PC}}{{\text{l}}_{\text{3}}}}}{\text{A}}\xrightarrow[\begin{subarray}{l}
{\text{Pd - BaS}}{{\text{O}}_{\text{4}}} \\ \left( {{\text{Step}}{\mkern 1mu} {\text{ - }}{\mkern 1mu} {\text{2}}} \right) \end{subarray} ]{{{{\text{H}}_{\text{2}}}}}{\text{B}}{\text{.}}\]
Step - 2 reaction is not suitable to prepare a compound (P). Which of the following test is used to distinguish compound B and P ?