A computer model records two changes involving an unstable nucleus.
Nucleus P emits radiation X and becomes nucleus Q. Nucleus Q then emits gamma radiation and becomes nucleus R.
| nucleus | number of protons | number of neutrons |
|---|---|---|
| P | 90 | 140 |
| Q | 88 | 138 |
Determine the mass number of nucleus P and the mass number of nucleus Q.
Use the information in the table to name radiation X.
State the number of protons and the number of neutrons in nucleus R.
State whether nucleus R has more energy, less energy or the same energy as nucleus Q.