Chloroform,when kept open,is oxidized to

The $S_N2$ product of the following reaction is:

$A$ haloalkane undergoes $S_{N}2$ or $S_{N}1$ reaction depending on

Classify the following reactions into one of the reaction types studied in this unit:
$(a)$ $CH_3CH_2Br + HS^{-} \rightarrow CH_3CH_2SH + Br^{-}$
$(b)$ $(CH_3)_2C=CH_2 + HCl \rightarrow (CH_3)_2ClC-CH_3$
$(c)$ $CH_3CH_2Br + HO^{-} \rightarrow CH_2=CH_2 + H_2O + Br^{-}$
$(d)$ $(CH_3)_3C-CH_2OH + HBr \rightarrow (CH_3)_2CBr-CH_2CH_3 + H_2O$

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?

Explain the following with examples: $(a)$ $\alpha$ and $\beta$-hydrogen,$(b)$ $\beta$-elimination reaction,and $(c)$ Saytzeff rule.