FBISE, NCP & NBF-aligned resources for Classes 9–12
Browse by Class
Browse by Type
Chemistry Chapter 3 : Topic 16
Uses of Isotopes
1 / 20
A scientist finds a fossilized bone and wants to estimate its age. The most suitable method involves measuring the decay of a radioactive isotope that naturally exists in living organisms and decreases after death. Which isotope is mainly used in this method?
Reasoning: Carbon-14 is a radioactive isotope that decays at a known rate after the organism dies, making it ideal for carbon dating.
2 / 20
Carbon dating is based on the principle that:
Reasoning: Carbon-14 undergoes radioactive decay into nitrogen-14 at a constant half-life.
3 / 20
A dead plant sample shows very low Carbon-14 content. This indicates that:
Reasoning: Low Carbon-14 means most of it has decayed, indicating an old sample.
4 / 20
In carbon dating, scientists measure the remaining amount of Carbon-14. The main reason this method works is:
Reasoning: A fixed half-life allows age estimation based on decay rate.
5 / 20
Which statement best describes the role of isotopes in medicine?
Reasoning: Radioisotopes are widely used in medical imaging and treatment.
6 / 20
A patient is injected with a small amount of radioactive tracer to observe blood flow in the brain. This technique is called:
Reasoning: Radioisotopes are used as tracers in imaging organs.
7 / 20
Which property makes isotopes useful in medical imaging?
Reasoning: Emitted radiation can be detected to form images of internal organs.
8 / 20
In a hospital, Technetium-99m (Tc-99m) is commonly used because it:
Reasoning: Short half-life reduces damage and gamma rays allow imaging.
9 / 20
A fossil is tested and found to contain very little radioactive carbon. What conclusion is most accurate?
Reasoning: Decreased Carbon-14 indicates long decay time ⟹ ancient fossil.
10 / 20
Which isotope is most commonly used to study thyroid gland disorders?
Reasoning: Iodine-131 accumulates in the thyroid and emits radiation for diagnosis / treatment.
11 / 20
The half-life of Carbon-14 is approximately:
Reasoning: Carbon-14 has a half-life of about 5730 years, used in dating ancient remains.
12 / 20
In medical imaging, isotopes are used mainly because they:
Reasoning: Radiation emitted helps create images of internal body structures.
13 / 20
A living tree contains Carbon-14, but a dead tree trunk does not show the same level. This difference is because:
Reasoning: Living organisms exchange carbon; after death, no intake occurs and decay starts.
14 / 20
Which of the following best explains why isotopes are suitable for tracing biological processes?
Reasoning: Isotopes behave like normal atoms chemically but can be traced due to radiation.
15 / 20
A doctor wants to detect a tumor inside a patient without surgery. The best method involves:
Reasoning: Radioisotopes help locate abnormal tissues through imaging.
16 / 20
Which statement correctly connects isotopes with archaeology?
Reasoning: Carbon dating helps determine the age of archaeological samples.
17 / 20
Why is Carbon-14 not used for dating very old rocks (millions of years old)?
Reasoning: Its half-life is too short for very ancient samples.
18 / 20
The effectiveness of isotopes in medical imaging depends on:
Reasoning: Detectable radiation is essential for producing diagnostic images.
19 / 20
A key advantage of using isotopes in medicine is that they:
Reasoning: Isotopes allow internal imaging without surgery (non-invasive).
20 / 20
Carbon dating becomes less accurate for extremely recent samples because:
Reasoning: Very small changes in Carbon-14 make measurement less precise for recent samples.
Your score is
Restart quiz