A compound ${\mathrm{C}}_5{\mathrm{H}}_{10}\mathrm{O}$ gives a positive test of carbonyl group, a negative test with Fehling solution, a positive haloform test and on reduction it gives normal pentane. Identify the compound. 

 Above conversion can be achieved by-

Choose the best combination of pair of compounds that undergo aldol condensation followed by dehydration to produce but-$2$-enal.

IUPAC name of the compound

The compounds $\mathrm{A}$ and $\mathrm{B}$ in the reaction sequence

$\mathrm{A}\stackrel{\mathrm{Phenol}}{⟵}{\mathrm{CH}}_3\mathrm{COCl}\stackrel{{\mathrm{CH}}_3\mathrm{COONa}}{⟶}\mathrm{B}$