Question

Caffeine has a molecular weight of 194.1 g/l. It contains 28.9% by mass of nitrogen, number of atoms of nitrogen in one molecule of caffeine is

• A. 4
• B. 6
• C. 5
• D. 3

Hint:

To determine the number of nitrogen atoms in a molecule, calculate the mass of nitrogen in one mole of the compound and divide by the atomic mass of nitrogen.

Answer 1

The Correct Option is D

By calculating the mass of nitrogen in a single molecule and using the molar mass of nitrogen, we determine that there are three nitrogen atoms in a caffeine molecule.