A researcher records the numbers of protons and neutrons in a nucleus before and after its first decay. The radiation emitted in this decay was not recorded.
| Measurement | Number of protons | Number of neutrons |
|---|---|---|
| Before the first decay | 7 | 10 |
| After the first decay | 8 | 9 |
The detector later records a second emitted particle with mass number 1 and charge number 0.
The nucleus left after the second emission is excited and then emits gamma radiation.
Identify the type of the first decay. Explain how the emitted particle is produced inside the nucleus.
Calculate the mass number immediately after the second emission. State whether the nucleus left after this emission belongs to the same element as the nucleus formed in the first decay. Give a reason for your answer.
Predict the mass number after the gamma emission and explain what happens to the energy of the nucleus.