What is the chemical formula for urea?

The correct chemical formula for urea is represented as NH₂-C(=O)-NH₂. This structure indicates that urea consists of a carbon atom (C) double-bonded to an oxygen atom (O) and single-bonded to two amine groups (NH₂). The presence of the carbonyl group (C=O) is crucial, as it characterizes urea's functional group as a carbamide, making it a key compound in biological processes and nitrogen metabolism.

In this representation, the C(=O) signifies the carbon center in the middle of the molecule, flanked by two amine groups, which highlights how the molecule is structured. Additionally, the connectivity between the carbon and the nitrogen atoms is essential in visualizing the compound's geometry and understanding its reactivity.

The other choices do not accurately depict urea’s structure. For instance, while the first option presents a similar idea, it does not clearly indicate the carbon double bond to oxygen, which is critical for urea's identity. The third option alters the bonding pattern unexpectedly, and the fourth option incorrectly represents the functional groups, including an alcohol function which does not belong to urea. Thus, the formulation NH₂-C(=O)-