Radioactivity Practice Questions
SPM (Malaysia) · SPM Physics · 136 free MCQs with instant results and detailed explanations.
136
Total
43
Easy
67
Medium
26
Hard
Start Practicing Radioactivity
Take a timed quiz or customize your practice session
Sample Questions from Radioactivity
Here are 10 sample questions. Start a quiz to get randomized questions with scoring.
Q1
Easy
What type of radiation consists of high-energy photons and is emitted during radioactive decay?
A.
Alpha particles
B.
Beta particles
C.
Gamma rays
D.
Neutrons
Show Answer & Explanation
Correct Answer: C
Gamma rays are high-energy electromagnetic waves emitted during radioactive decay. Unlike alpha and beta particles, they carry no charge and are not made up of matter, which makes them highly penetrating.
Q2
Easy
If a radioactive substance has a half-life of 5 years, how much of a 200g sample will remain after 15 years?
A.
25g
B.
50g
C.
100g
D.
75g
Show Answer & Explanation
Correct Answer: A
After 15 years, which is three half-lives (5 years each), the sample decreases as follows: 200g -> 100g -> 50g -> 25g. Therefore, 25g remains.
Q3
Easy
Which of the following is a common application of radioactivity in medicine?
A.
Food preservation
B.
Radiotherapy for cancer treatment
C.
Smoke detectors
D.
Mineral dating
Show Answer & Explanation
Correct Answer: B
Radiotherapy uses radioactive isotopes to target and destroy cancer cells. This method is a significant medical application of radioactivity, differentiating it from other options listed.
Q4
Medium
What type of radiation is emitted during the decay of a Uranium-238 nucleus?
A.
Alpha particles
B.
Beta particles
C.
Gamma rays
D.
X-rays
Show Answer & Explanation
Correct Answer: A
Uranium-238 primarily emits alpha particles during its decay process, making option A correct. Alpha decay involves the release of helium nuclei, which is characteristic of heavy nuclei like Uranium.
Q5
Medium
Which of the following statements about gamma radiation is true?
A.
It has mass and charge.
B.
It is highly penetrating.
C.
It causes significant ionization in matter.
D.
It can be easily stopped by paper.
Show Answer & Explanation
Correct Answer: B
Gamma radiation is highly penetrating due to its electromagnetic nature, unlike alpha and beta particles, which have mass and charge. Therefore, option B is correct.
Q6
Medium
If a sample of carbon-14 has a radioactivity of 1600 Bq at the start, what will its radioactivity be after 2 half-lives?
A.
400 Bq
B.
800 Bq
C.
200 Bq
D.
1000 Bq
Show Answer & Explanation
Correct Answer: A
After two half-lives, the activity will reduce to 1600/(2^2) = 1600/4 = 400 Bq, making option A the correct answer.
Q7
Medium
In a radioactive decay series, if element A decays into element B, which then decays into element C, what can be said about the stability of these elements?
A.
Element A is always the most stable.
B.
Element B is often more stable than element C.
C.
Element C is always the least stable.
D.
Element A is typically less stable than element B.
Show Answer & Explanation
Correct Answer: D
In decay series, element A often has a higher energy state and is less stable than element B, which forms from its decay. Thus, option D is correct.
Q8
Hard
A sample contains three types of radioactive isotopes: A, B, and C. Isotope A has a half-life of 5 years, isotope B has a half-life of 10 years, and isotope C has a half-life of 15 years. If we start with 80 grams of isotope A, 160 grams of isotope B, and 240 grams of isotope C, how much of each isotope will remain after 30 years?
A.
5 grams, 20 grams, 60 grams
B.
10 grams, 40 grams, 80 grams
C.
20 grams, 80 grams, 120 grams
D.
40 grams, 60 grams, 80 grams
Show Answer & Explanation
Correct Answer: A
After 30 years, isotope A undergoes 6 half-lives (30/5), leaving 80/(2^6) = 5 grams. Isotope B undergoes 3 half-lives (30/10), leaving 160/(2^3) = 20 grams. Isotope C undergoes 2 half-lives (30/15), leaving 240/(2^2) = 60 grams.
Q9
Hard
A sample of radioactive material has a half-life of 5 years. If you start with 80 grams of the material, how much will remain after 15 years?
A.
10 grams
B.
20 grams
C.
40 grams
D.
5 grams
Show Answer & Explanation
Correct Answer: A
After 15 years, which is three half-lives (5 years each), the remaining amount is 80 grams divided by 2^3 (or 8), resulting in 10 grams.
Q10
Hard
If a radioactive isotope has an activity of 240 Bq at time t=0, and its activity decreases to 30 Bq after 20 years, what is the approximate half-life of the isotope?
A.
5 years
B.
10 years
C.
15 years
D.
20 years
Show Answer & Explanation
Correct Answer: C
The decrease from 240 Bq to 30 Bq indicates a reduction through several half-lives. Approximately 3 half-lives have elapsed, suggesting each half-life is about 5 years, totaling around 15 years for 3 half-lives.
Showing 10 of 136 questions. Start a quiz to practice all questions with scoring and timer.
Practice All 136 Questions →Other SPM (Malaysia) Subjects
Radioactivity — SPM (Malaysia) SPM Physics Practice Questions Online
This page contains 136 practice MCQs for the chapter Radioactivity in SPM (Malaysia) SPM Physics. The questions are organized by difficulty — 43 easy, 67 medium, 26 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.