Which of the following chloro-compounds shows complete inversion of configuration during a reaction?

Select the incorrect order among the following:

Compound $(A), \, C_8H_9Br,$ gives a white precipitate when warmed with alcoholic $AgNO_3.$ Oxidation of $(A)$ gives an acid $(B), \, C_8H_6O_4.$ $(B)$ easily forms anhydride on heating. Identify the compound $(A).$

At normal temperature,iodoform is:

The following bimolecular elimination reaction $(E_2)$ is carried out with different halogen leaving groups. The per cent yield of the two products ($2$-hexene and $1$-hexene) for each leaving group is listed below.

Leaving group	Conj. Acid $pK_a$	$\%$-yield of $2$-hexene	$\%$-yield of $1$-hexene
$X = I$	$-10$	$81\%$	$19\%$
$X = Br$	$-9$	$72\%$	$28\%$
$X = Cl$	$-7$	$67\%$	$33\%$
$X = F$	$3.2$	$30\%$	$70\%$

Which of the following statement$(s)$ is/are true concerning this series of $E_2$ reactions?

Vinyl chloride reacts with $HCl$ to form