The compound used as hypnotic under the name "hypnone" is
Acetophenone
The question asks to identify the chemical compound historically known as "hypnone" and used for its hypnotic properties. Understanding the common names and historical uses of organic compounds is important in chemistry.
The compound referred to as "hypnone" is chemically known as Acetophenone. It is an organic compound with the chemical formula \(\text{C}_6\text{H}_5\text{COCH}_3\). This structure consists of a phenyl group (\(\text{C}_6\text{H}_5\)) attached to a carbonyl group (\(\text{CO}\)), which is then attached to a methyl group (\(\text{CH}_3\)).
Let's briefly look at why the other options are not the compound "hypnone":
Based on chemical nomenclature and historical usage, Acetophenone is definitively the compound known as "hypnone" and used as a hypnotic.
Whose Periodic Law was modified and adopted the Atomic number as the basis of Modern Periodic Table?