Glyoxal $(OHC-CHO)$ on being heated with concentrated $NaOH$ forms:

Which of the following reagents can be used for the given chemical transformation?

Two moles of benzaldehyde and one mole of acetone under alkaline conditions using aqueous $NaOH$ after heating gives $x$ as the major product. The number of $\pi$ bonds in the product $x$ is.................

Arrange the following compounds in increasing order of their enol content:
$1. CH_3CHO$
$2. CH_3COCH_3$
$3. CH_3COCH_2CHO$
$4. CH_3COCH_2COCH_3$

Which of the following compounds containing a carbonyl group will give a coloured crystalline compound with $2, 4-DNP$?

$C_6H_5-CO-CHO$ $\xrightarrow{conc. OH^-} (A)$ $\xrightarrow{H_3O^+} (B)$ $\xrightarrow[2. NaOH/CaO/\Delta]{1. KMnO_4} (C)$
Product $(C)$ is: