Nuclear Chemistry — Drills · Grade 11 Science
Chapter: Redox, Cells & Nuclear ChemistryWhat these drills covers
By the end of Nuclear Chemistry you should be able to:
- I can describe alpha, beta, and gamma decay and write balanced nuclear equations for them.
- I can use half-life to calculate how much of a radioactive sample remains after a given time.
- I can compare nuclear fission and fusion as processes that convert mass into enormous amounts of energy.
6 questions, multiple choice, numeric and written answer, each with a worked explanation.
Vocabulary used: radioactivity, alpha decay, beta decay, gamma decay, half-life, nuclear fission, nuclear fusion.
Problem 1
- a free neutron
- a beta particle
- an alpha particle
- a gamma ray
Answer and explanation
an alpha particle
An alpha particle is a helium-4 nucleus, ⁴₂He — two protons and two neutrons.
Problem 2
- one quarter
- none of it
- all of it
- one half
Answer and explanation
one half
One half-life is, by definition, the time it takes for half of the sample to decay, leaving one half behind.
Problem 3
Answer and explanation
40 g
15 ÷ 5 = 3 half-lives, so the sample halves three times: 320 → 160 → 80 → 40 g (or 320 ÷ 2³ = 40 g).
Problem 4
- both decrease
- both stay the same
- both increase
- only the mass number changes
Answer and explanation
both stay the same
A gamma ray carries away energy but no mass and no charge, so the mass number and atomic number are both unchanged.
Problem 5
Answer and explanation
In fusion, light nuclei are forced together into a heavier nucleus, and a tiny amount of mass is converted directly into energy according to E = mc², releasing an enormous amount of energy. The most important example is the Sun, where hydrogen nuclei fuse into helium, producing the light and heat that reach Earth.
Problem 6
Answer and explanation
32 days
Halving from 96 g: 96 → 48 → 24 → 12 → 6 g is 4 half-lives (96 ÷ 2⁴ = 6 g). Four half-lives × 8 days = 32 days.