Class 10 Radioactivity Mock Test (ICSE)

Topics in Radioactivity

• Structure of the nucleus
• Alpha, beta and gamma radiations
• Changes in the nucleus on emission
• Uses and dangers of radiation
• Nuclear fission and fusion

Radioactivity practice questions with answers

1. Q1Multiple choice·1 mark
   Which of the following statements is correct regarding a nuclear fusion reaction?

   1. (a)It takes place at extremely high temperatures and high pressure.
   2. (b)It does not release any energy.
   3. (c)It is commonly used in nuclear power reactors for electricity generation.
   4. (d)It involves the splitting of a heavy nucleus into two lighter nuclei.
   Show answer and step marks

   1. Correct option: (a) It takes place at extremely high temperatures and high pressure.+1

   Answer: (a)
2. Q2Multiple choice·1 mark
   Which of the following radiations is most suitable for detecting internal cracks and flaws in metal castings due to its high penetrating power?

   1. (a)$\gamma$-radiations
   2. (b)Ultraviolet radiations
   3. (c)$\beta$-radiations
   4. (d)$\alpha$-radiations
   Show answer and step marks

   1. Correct option: (a) $\gamma$-radiations+1

   Answer: (a)
3. Q3Short answer·2 marks
   A radioactive nucleus $_{92}^{238}\text{U}$ emits one $\alpha$-particle followed by two $\beta$-particles. Determine the mass number and atomic number of the resulting final nucleus.
   Show answer and step marks

   1. Emission of one $\alpha$-particle decreases the mass number by $4$ and the atomic number by $2$, giving a nucleus with mass number $234$ and atomic number $90$.+1
   2. Emission of $\beta$-particles does not change the mass number, so the final mass number is $234$.+0.5
   3. Each $\beta$-particle increases the atomic number by $1$, so after two of them the final atomic number is $90 + 2 = 92$.+0.5

   Answer: Mass number = $234$, Atomic number = $92$
4. Q4Short answer·2 marks
   A radioactive nucleus $_Z^A X$ emits one $\alpha$-particle followed by two $\beta$-particles. Determine the mass number and atomic number of the resulting daughter nucleus.
   Show answer and step marks

   1. Emission of one $\alpha$-particle changes the nucleus to $_{Z-2}^{A-4}X'$, reducing the mass number by $4$ and the atomic number by $2$.+1
   2. Emission of $\beta$-particles does not change the mass number, so the final mass number is $A - 4$.+0.5
   3. Each $\beta$-particle increases the atomic number by $1$, so after two of them the final atomic number is $(Z - 2) + 2 = Z$.+0.5

   Answer: Mass number = $A - 4$, Atomic number = $Z$
5. Q5Long answer·4 marks
   (a) State two uses of radioisotopes in the field of medicine. (b) Mention two safety precautions that must be taken while handling radioactive materials.
   Show answer and step marks

   1. (a) First medical use, any one of: cobalt-60 (gamma rays) in radiotherapy to destroy cancer cells; iodine-131 as a tracer to study the thyroid and treat thyroid disorders; radioactive tracers to locate tumours or blood clots; gamma rays to sterilise surgical instruments and dressings; or any other valid medical use.+1
   2. (a) Second medical use, a different one from the same list.+1
   3. (b) First precaution, any one of: handle sources with long tongs or remote-controlled tools to keep a safe distance; store sources in thick lead containers; wear lead-lined aprons and gloves; wear a film badge (dosimeter) to monitor the dose received; never eat, drink or touch the face in the work area and limit exposure time; or any other valid precaution.+1
   4. (b) Second precaution, a different one from the same list.+1

   Answer: (a) Any two of: cobalt-60 radiotherapy for cancer; iodine-131 for thyroid study and treatment; tracers to locate tumours or clots; sterilising surgical instruments. (b) Any two of: handle sources with long tongs or remote tools; store them in thick lead containers; wear lead aprons and gloves; wear a film badge to monitor dose; limit exposure time and do not eat or drink nearby.
6. Q6Long answer·4 marks
   (a) State two safety precautions that must be observed while handling radioactive substances, along with the scientific reason for each. (b) Mention one specific use of radioactivity in each of the following fields: (i) Medicine (ii) Agriculture
   Show answer and step marks

   1. (a) First precaution with its reason, any one of: handle sources with long-handled tongs or remote-controlled tools, because the radiation reaching the body decreases rapidly with distance; store sources in thick lead containers, because lead absorbs the radiation and shields people nearby; wear lead-lined aprons and gloves, because lead absorbs radiation that would otherwise reach the body; wear a film badge (dosimeter), because it records the cumulative dose so that over-exposure can be detected (it does not itself protect); keep exposure time as short as possible, because the dose received increases with time; or any other valid precaution with its reason.+1
   2. (a) Second precaution with its reason, a different one from the same list.+1
   3. (b)(i) Use in medicine, any one of: cobalt-60 in radiotherapy to destroy cancer cells; iodine-131 to study and treat the thyroid; tracers to locate tumours; sterilising surgical instruments; or any other valid medical use.+1
   4. (b)(ii) Use in agriculture, any one of: phosphorus-32 as a tracer to study the uptake of fertiliser by plants; gamma irradiation to preserve food grains and other produce; radiation-induced mutation to develop high-yielding crop varieties; sterilising insect pests; or any other valid agricultural use.+1

   Answer: (a) Any two of, with reasons: long tongs or remote handling (radiation falls with distance); thick lead containers (lead absorbs radiation); lead aprons and gloves (shield the body); film badge (monitors cumulative dose); minimum exposure time (dose grows with time). (b)(i) e.g. cobalt-60 radiotherapy for cancer; (ii) e.g. phosphorus-32 tracer to study fertiliser uptake by plants.

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