Difficulty: Medium
Average Score: 70%
Entry Exam
Passage / Scenario
If A represents atomic mass and Z represents atomic number, which of the following describes an atom after a proton is emitted from its nucleus?
Correct answer
D
Rationale
When a proton is emitted from the nucleus of an atom, the atomic mass (A) remains the same while the atomic number (Z) decreases by 1. This is because a proton carries a positive charge and has a mass of 1 atomic mass unit. Therefore, the correct description after the emission of a proton is A-1, Z-1. The atomic mass decreases by 1 because a proton is lost, and the atomic number decreases by 1 since the nucleus loses a positively charged particle.