$\begin {array} {1 1} (A)\;H(COO)_2ca+(H_3CCOO)_2ca \underrightarrow {\Delta}\: \: \:2CH_3CHO+H_2 \\ (B)\;CH_3CH(OH)CH_3 \underrightarrow {cu / 300^{\circ}C} \: \: \: CH_3COCH_3+h_2 \\ (C)\;CH_3CH_2OH \underrightarrow {Ag/ 300^{\circ}C} \: \: \: Ch_3CHO+H_2\\ (D)\;CH_2 = CH_2+PdCl_2+H_2O \overset{\overset{CaCl_2}{\longrightarrow}}{H^{\oplus}} \: \: \: CH_3CHO+pd+2HCl \end {array}$
