HgSO_(4) 9. A+Barrow HCequiv CHxrightarrow (-272)arrow Axrightarrow [C_(2),H_(2)H_(2)Br}(-27)Bxrightarrow [Delta ](NaH)Cxrightarrow [CH_(3)Cl](C_(2)Cl)Dxrightarrow [Cl_(2)](Cl_(2))D

The correct answer is D.<br /><br />Explanation:<br />The given chemical reactions represent a series of transformations involving different compounds. Let's break down the reactions step by step:<br /><br />1. $HC\equiv CH$ (acetylene) undergoes a reaction with hydrogen bromide ($HBr$) to form $C_{2}H_{2}Br$ (vinyl bromide).<br />2. $C_{2}H_{2}Br$ then reacts with sodium hydride ($NaH$) to form $C_{2}H_{2}$ (acetylene).<br />3. $C_{2}H_{2}$ reacts with chlorine ($Cl_{2}$) to form $C_{2}Cl_{2}$ (dichloroethene).<br />4. $C_{2}Cl_{2}$ then reacts with $CH_{3}Cl$ (methyl chloride) to form $D$ (which is $C_{2}H_{2}Cl_{2}$).<br />5. Finally, $D$ reacts with chlorine ($Cl_{2}$) to form $D$ again.<br /><br />Therefore, the final product of the given reactions is $D$, which is $C_{2}H_{2}Cl_{2}$.