Identify the product $(C)$ in the following reaction sequence:
$CH_3-CH(Cl)-CH(Cl)-COO^-$ $\xrightarrow{-CO_2} A$ $\xrightarrow{HCl} B$ $\xrightarrow{aq. KOH} C$

Answer the following questions:
$(i)$ What is the bond length of $C-C$,$C=C$,and $C\equiv C$?
$(ii)$ What will be the effect on bond length as bond multiplicity increases?
$(iii)$ What is the relation between reactivity of compound,bond strength and bond order between two carbon atoms?
$(iv)$ What is the rate of reaction of $Cl_2, Br_2,$ and $I_2$ with $CH_2=CH_2$?
$(v)$ What is the difference between $2-$butyne and $1-$butyne? By which test can we distinguish between these two?
$(vi)$ Which real product is obtained on hydrolysis of alkyne? Why?
$(vii)$ Give the structure and $IUPAC$ name:
$(a)$ Vinyl chloride
$(b)$ Vinyl cyanide
$(c)$ Glyoxal
$(d)$ Silver acetylide
$(e)$ Diacetyl
$(f)$ Glycol

The hottest region of the Bunsen flame shown in the figure below is:

The inorganic origin of petroleum is indicated by the fact that

In which of the following reactions does an acid-base reaction take place?

Identify $(A)$.