In basic chemistry, which chemical elements are present in the organic compound urea (CO(NH2)2)?

Introduction / Context:
Urea is one of the most important organic compounds in basic chemistry and biochemistry. It is widely used as a nitrogen rich fertilizer in agriculture and is also an important metabolic waste product in many living organisms. To answer questions about its composition, you must be familiar with its molecular formula and understand which chemical elements are present in that formula. This type of question checks your understanding of chemical notation and elemental composition of a well known compound.

Given Data / Assumptions:

• The compound under discussion is urea.
• The molecular formula of urea is CO(NH2)2.
• We assume standard chemical notation where C is carbon, H is hydrogen, O is oxygen and N is nitrogen.
• The task is simply to identify which elements appear in the formula, not how many atoms of each are present.

Concept / Approach:
The molecular formula of a compound lists the symbols of all elements present in a single molecule. Subscripts show the number of atoms of each element, but for this question we only need to know which symbols appear at all. Urea is written as CO(NH2)2. By carefully reading the formula from left to right, you can list each distinct element symbol. Once you identify carbon, oxygen, nitrogen and hydrogen in the formula, you match that list with the options given in the question stem.

Step-by-Step Solution:
Step 1: Write the molecular formula of urea clearly: CO(NH2)2.Step 2: Identify the first element symbol C, which stands for carbon.Step 3: Identify the next element symbol O, which stands for oxygen.Step 4: Inside the parentheses, note the symbol N for nitrogen.Step 5: Also inside the parentheses, note the symbol H for hydrogen.Step 6: Collect the distinct elements: C, O, N and H. This matches the option that lists all four of these elements together.

Verification / Alternative check:
An alternative way to check is to break urea into its functional parts. The central portion resembles a carbonyl group (C=O), which clearly contains carbon and oxygen. On each side of the carbonyl carbon there is an NH2 group, known as an amino group, which contains nitrogen and hydrogen. When you join these parts into the full molecule CO(NH2)2, both amino groups and the carbonyl group are still present. Therefore, all four elements carbon, oxygen, nitrogen and hydrogen must be part of the molecule. This confirms the list of elements we identified earlier.

Why Other Options Are Wrong:
Option a, C, H, O, omits nitrogen even though NH2 groups are clearly present. Option b, C, N, O, leaves out hydrogen, which is essential in the NH2 groups. Option c, C, N, H, incorrectly leaves out oxygen, even though there is a carbonyl oxygen in the CO part of the formula. Each of these options misses at least one element from the correct set, so they cannot represent the full elemental composition of urea.

Common Pitfalls:
A frequent mistake is to overlook elements that appear only once or to misread the formula by focusing only on the central CO portion and forgetting the attached NH2 groups. Students may also confuse the number of atoms with the number of elements and overthink the problem. To avoid these issues, always scan the entire formula and list each distinct element symbol at least once. Remember that subscripts, parentheses and coefficients affect atom counts but not the identity of the elements themselves.

Final Answer:
Urea contains the four elements carbon, oxygen, nitrogen and hydrogen (C, O, N, H) in its molecular formula CO(NH2)2.