Question

a scientist is examining the role of an element found in fats and carbohydrates of living things. this element makes up 65% of human body mass. which statement describes the element he is studying? he is studying oxygen, which can also be found in proteins. he is studying oxygen, which is the most abundant element in the atmosphere. he is studying nitrogen, which can also be found in proteins. he is studying nitrogen, which is the most abundant element in the atmosphere.

Explanation:

• First, identify the element. Oxygen makes up about 65% of human body mass. Nitrogen makes up only about 3% of human body mass.
• Then, check the properties. Oxygen is found in fats (e.g., triglycerides have oxygen), carbohydrates (e.g., glucose \(C_6H_{12}O_6\) has oxygen), and proteins (e.g., amino - acids have oxygen in the carboxyl group \(-COOH\)). Nitrogen is in proteins (in the amino group \(-NH_2\)) but not in the typical structure of fats and carbohydrates.
• Also, the most abundant element in the atmosphere is nitrogen (about 78% of the atmosphere is \(N_2\)), not oxygen (about 21% of the atmosphere is \(O_2\)).

Answer:

He is studying oxygen, which can also be found in proteins.