Name two drugs used in the treatment of cancer.

Assertion $(A)$: Shape of the receptor changes after attachment of chemical messenger.
Reason $(R)$: Receptor does not regain original shape after removal of chemical messenger.
The correct answer is

$A$ 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?

The chemical $X$ is used in the prevention of heart attack. The structure of $X$ is

Stearic acid and polyethylene glycol react to form which one of the following soaps/detergents?

Identify phenacetin from the following.