Which of the following compounds is known as carbamide?

The correct answer is urea, commonly known as carbamide. Urea is a simple organic compound with the formula (NH2)2CO. It plays a crucial role in the nitrogen cycle and is a major component of urine in mammals. The term "carbamide" reflects its structure, as it contains both a carbonyl (C=O) group and two amine (NH2) groups. This designation highlights its relationship to both carbon and amine functionalities.

The other options are not referred to as carbamide. Acetamide, for example, consists of an acetyl group attached to an amine group, while formamide has a similar structure but is based on formic acid. Glutaraldehyde is a dialdehyde and does not have the characteristic amine groups found in urea or carbamide. Thus, urea is uniquely referred to as carbamide, distinguishing it from these other compounds.