International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

What is the mass of a proton typically represented as?

1. 0

2. 1

3. 2

4. 1/2

The correct answer is: 1

The mass of a proton is typically represented as approximately 1 atomic mass unit (amu). In atomic physics, the atomic mass unit is defined as one twelfth of the mass of a carbon-12 atom, which makes the mass of a proton very convenient to represent as 1 for many calculations and comparisons involving atomic masses. This simplification is widely used within chemistry and physics, making calculations involving molecular weights and stoichiometry much easier. By using the value of 1 for the mass of a proton, students can quickly grasp concepts such as the relative weights of other particles and the composition of atoms. The other values do not accurately represent the mass of a proton in this context. The choice of 0 would imply the particle has no mass at all, which is incorrect. A representation of 2 would suggest that the proton is heavier than it is, while 1/2 would imply that it has less mass than half of its actual value. Thus, representing the mass of a proton as 1 is a practical and effective approach in the study of chemistry.