Question 19M.3.HL.TZ2.21
| Date | May 2019 | Marks available | [Maximum mark: 5] | Reference code | 19M.3.HL.TZ2.21 |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | Describe, Explain | Question number | 21 | Adapted from | N/A |
Explain the formation of a type I a supernova which enables the star to be used as a standard candle.
[3]
white dwarf attracts mass from another star ✔
explodes/becomes supernova when mass equals/exceeds the Chandrasekhar limit / 1.4MSUN ✔
hence luminosity of all type I a supernova is the same ✔
OWTTE
The formation of Type 1a supernovae was well known by most candidates but few were able to explain how this process resulted in a standard candle.
Describe the r process which occurs during type II supernovae nucleosynthesis.
[2]
«successive» rapid neutron capture ✔
faster than «β» decay can occur ✔
results in formation of heavier/neutron rich isotopes ✔
OWTTE
Many candidates could describe the r process correctly but quite a large number of candidates seemed completely at a loss and could not relate the r process to neutron capture.