Which substance,when added as an adulterant to ethanol used as an intoxicating drink,causes a person to lose their vision?

What is the role of the metal or reagents written on the arrows in the given chemical reactions?
$(a)$
$(b)$ $CH_{3}COOH + CH_{3}CH_{2}OH \xrightarrow{Conc. H_{2}SO_{4}} CH_{3}COOC_{2}H_{5} + H_{2}O$
$(c)$ $CH_{3}CH_{2}OH \xrightarrow[Heat]{Alkaline KMnO_{4}} CH_{3}COOH$

What is used to prepare white lead?

List two characteristics of covalent compounds.

Which of the following functional groups does not possess a double bond?

Draw the electron dot structure of ethane,$C_{2}H_{6}$.