The substances which affect the central nervous system and induce sleep are called

An example of a psychedelic agent is

Match List-$I$ with List-$II$:

List-$I$ (Class of Chemicals)	List-$II$ (Example)
$(a)$. Antifertility drug	$(i)$. Meprobamate
$(b)$. Antibiotic	$(ii)$. Alitame
$(c)$. Tranquilizer	$(iii)$. Norethindrone
$(d)$. Artificial Sweetener	$(iv)$. Salvarsan

An antibiotic with a broad spectrum:

What is the function of adding $Bithionol$ to soap?

$A$ chemist has $4$ samples of artificial sweetener $A, B, C$,and $D$. To identify these samples,he performed certain experiments and noted the following observations:
$(i)$ $A$ and $D$ both form blue-violet colour with ninhydrin.
$(ii)$ Lassaigne extract of $C$ gives positive $AgNO_{3}$ test and negative $Fe_{4}[Fe(CN)_{6}]_{3}$ test.
$(iii)$ Lassaigne extract of $B$ and $D$ gives positive sodium nitroprusside test.
Based on these observations,which option is correct?