A researcher checks records of nuclei detected in a meteorite. A reference nucleus has 14 protons and 16 neutrons.
Each record in the table claims to give another isotope of the reference nucleus and its mass number.
| Record | Number of protons | Number of neutrons | Stated mass number |
|---|---|---|---|
| P | 14 | 18 | 18 |
| Q | 16 | 14 | 30 |
| R | 15 | 16 | 31 |
| S | 14 | 15 | 29 |
Which record is correct?
Record P
Record Q
Record R
Record S