Identify the product ' B ' in the following sequence of reactions.

Methyl magnesium bromide $\xrightarrow{\mathrm{CdCl}_2} \mathrm{~A}\xrightarrow{\mathrm{CH}_3 \mathrm{COCl}} \mathrm{~B}$

What is the number of $>\mathrm{C}=\mathrm{C}<$ bonds present in a linolenic acid molecule?

Which among the following is an allylic halide?

When tert butyl bromide is heated with silver fluoride the major product obtained is