CIE iGCSE Co-Ordinated Science P5.1 The nucleus Exam Style Questions Paper 3
Question
(a) (i) Complete the sentences to describe the energy changes that occur during the generation of electricity in a nuclear power station.
Nuclear fission releases ………………………………………… energy which heats up water in a boiler.
When the turbine and generator are turning, they have ………………………………………… energy.
The generator produces ………………………………………… energy.
(ii) Nuclear fission occurs in the nuclear power station.
State what happens to the nucleus of an atom during nuclear fission.
(b) The radioactive decay of plutonium-239 produces an isotope of uranium, uranium-235.
plutonium-239 → uranium-235 + α-particle
(i) State the charge on an α-particle.
(ii) Describe how the numbers of protons and neutrons change in the nucleus of a plutonium-239 atom when it emits an α-particle.
protons …………………………………………………………………………
neutrons …………………………………………………………………………
(iii) The half-life of plutonium-239 is 24 000 years.
A sample of nuclear fuel contains 6.0 g of plutonium-239.
Calculate the mass of plutonium-239 remaining after 72 000 years.
mass = ……………………………………………… g
▶️Answer/Explanation
Ans : 6(a)(i) thermal ;
kinetic ;
electrical ;
6(a)(ii) splits ;
6(b)(i) (2) positive ;
6(b)(ii) protons decrease by 2 or down to 92 ;
neutrons decrease by 2 or down to 143 ;
6(b)(iii) 3 half lives ;
6.0 divided by 2 three times ;
0.75 (g) ;
Question
(a) Electricity is generated in a nuclear power station by the nuclear fission of plutonium-239. Describe what happens to a nucleus of plutonium-239 during nuclear fission.
▶️Answer/Explanation
During nuclear fission, the nucleus of plutonium-239 splits into two smaller nuclei, releasing a large amount of energy and several neutrons. This process is typically initiated by the absorption of a neutron by the plutonium-239 nucleus.
(b) Plutonium-239 is an isotope of plutonium.
(i) State the meaning of isotope.
▶️Answer/Explanation
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This results in isotopes having the same atomic number but different mass numbers.
(ii) Plutonium-239 emits β-radiation. Suggest how a small sample of plutonium-239 can be stored safely.
▶️Answer/Explanation
A small sample of plutonium-239 can be stored safely in a lead-lined container to shield against β-radiation. The container should be kept in a secure, controlled environment to prevent any leakage or exposure.
(iii) Plutonium-239 has a half-life of 24000 years. A sample of plutonium-239 has a mass of 800 g. Calculate the mass of plutonium-239 remaining after 48000 years.
▶️Answer/Explanation
After 48000 years, which is 2 half-lives, the mass of plutonium-239 remaining would be:
Initial mass = 800 g
After 1 half-life (24000 years): 800 g / 2 = 400 g
After 2 half-lives (48000 years): 400 g / 2 = 200 g
Therefore, the mass remaining after 48000 years is 200 g.
(iv) State two differences between β-radiation and γ-radiation.
▶️Answer/Explanation
1. Nature: β-radiation consists of high-energy electrons (or positrons), while γ-radiation consists of high-energy photons (electromagnetic waves).
2. Penetration: β-radiation is less penetrating than γ-radiation. β-particles can be stopped by a few millimeters of aluminum, whereas γ-rays require several centimeters of lead or concrete to be effectively shielded.
(v) Fig. 12.1 shows an incomplete electromagnetic spectrum. Place γ-radiation in its correct place in Fig. 12.1.
▶️Answer/Explanation
γ-radiation should be placed at the far right end of the electromagnetic spectrum, as it has the highest frequency and shortest wavelength among the types of electromagnetic radiation.