Pyrolysis of acetone gives $CH_2=C=O$ called

In the above reaction,product $(B)$ is:

Give the conversion of the following:
$(i)$ Benzoic acid from Bromobenzene
(ii) $2$-methylbutan-$2$-ol from Propenone

The reaction sequence is as follows:
Benzene + $CH_3COCl$ $\xrightarrow{\text{Anhydrous } AlCl_3} (A)$ $\xrightarrow{(x)} \text{Ethylbenzene}$.
Reagent $(x)$ can be:

What are $A, B, C$ and $D$ in the following cross-aldol condensation reaction?
$\text{Propanal} + \text{Ethanal} \xrightarrow[ii) \ \Delta]{i) \ NaOH} A + B + C + D$
(The products are the four possible $\alpha,\beta$-unsaturated aldehydes formed by self and cross-aldol condensation followed by dehydration.)

Identify the reagent $R$ used in the following reaction:
$\text{Ketone} \xrightarrow{R} \text{Semicarbazone}$