The structure of ranitidine is:

The $-As=As-$ linkage is present in which of the following medicines?

Correct statements with respect to morphine $(X)$ and Veronal $(Y)$ are:
$A$. Both $X$ and $Y$ are sleep-producing agents.
$B$. $X$ is hypnotic and $Y$ is analgesic.
$C$. $X$ is analgesic and $Y$ is hypnotic.
$D$. $X$ is non-narcotic analgesic and $Y$ is antidepressant.

Which of the following is an analgesic?

The following molecule with the structure acts as:

Sulfa drugs are used as