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Class 10 Physics Chapter 9: Chapter 9 MCQs With Explanations
Practice Class 10 Physics Chapter 9: Chapter 9 MCQs with explanations for Pakistani board exams. Includes solved objective questions, answer checking, chapter revision guidance and next chapter suggestions.
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Carbon-14 decays after death, and the known half-life allows age estimation by measuring remaining carbon-14 levels.
Q2. When a heavy nucleus splits into two lighter nuclei, the process would
Nuclear fission of heavy nuclei releases binding energy in the form of nuclear energy due to mass defect.
Q3. Release of energy by the Sun is due to
The Sun generates energy through nuclear fusion, where hydrogen nuclei combine to form helium, releasing vast amounts of energy.
Q4. When uranium (92 protons) ejects a beta particle, how many protons will be in the remaining nucleus?
Beta decay converts a neutron to a proton, increasing atomic number by 1: 92 + 1 = 93 protons.
Q5. The half–life of a certain isotope is 1 day. What is the quantity of the isotope after 2 days.
After one half-life (1 day), half remains; after two half-lives (2 days), one-quarter remains.
Q6. What happens to the atomic number of an element that emits one alpha particle and one beta particle?
Alpha emission reduces atomic number by 2; beta emission increases it by 1; net change is zero.
Q7. Which among the following radiations has more penetrating power?
Gamma rays are high-energy photons with no mass or charge, allowing them to penetrate matter more deeply than alpha or beta particles.
Q8. One of the isotopes of uranium is 23892U, The number of neutrons in this isotope is
Neutrons = mass number - atomic number = 238 - 92 = 146.
Q9. How many naturally occurring isotopes does carbon have?
Carbon has six known isotopes, but only three are stable: C-12, C-13, and C-14 is radioactive; however, six isotopes are recognized in total including unstable ones.
Q10. The elements which emits radiations are called as:
Radioactive elements are those with unstable nuclei that spontaneously emit radiation, regardless of isotopic form.
Q11. The process in which two light nuclei combine to form heavier nucleus is called
Nuclear fusion involves combining light nuclei under high temperature and pressure to form a heavier nucleus, releasing energy.
Q12. Breaking of heavy nucleus in to smaller nuclei is called
Nuclear fission involves splitting a heavy nucleus into lighter nuclei, releasing energy and neutrons.
Q13. Half-life of plutonium-236 is
The accepted half-life of plutonium-236 is approximately 2.65 years, based on nuclear data references.
Q14. Artificially produced radioactive elements by bombardment of different particles are called
Radioisotopes are unstable isotopes created artificially through nuclear reactions like particle bombardment.
Q15. Becquerel is denoted by
The SI unit of radioactivity, becquerel, is symbolized as Bq, representing one decay per second.
Q16. The recommended annual radiation exposure limit for patients undergoing medical imaging is
Medical exposure limits vary by procedure, but typical effective doses for diagnostic imaging range from 0.1 to 10 rem annually.
Q17. What is the safe limit of radiation exposure per year
The recommended annual radiation exposure limit for the general public is 5 rem (50 mSv) according to international safety guidelines.
Q18. Nuclear radiation activity is measured in
Becquerel (Bq) is the SI unit for measuring radioactive decay rate, defined as one disintegration per second.
Q19. Radioactive elements are also called as
Radioisotopes are isotopes of elements that are radioactive due to unstable nuclei, making this the precise scientific term.
Q20. Leukemia is
Leukemia is a type of cancer that affects the blood and bone marrow, characterized by abnormal proliferation of white blood cells.
Q21. What is the approximate temperature at the core of the Sun?
The Sun's core temperature is approximately 15 million K, and 20 million K is a commonly accepted rounded value in educational materials.
Q22. When deuterium is fused with tritium, what is primarily produced?
Deuterium-tritium fusion produces a helium-4 nucleus and a neutron, with the excess energy released as high-energy gamma radiation (γ-particles).
Q23. The half-life period of uranium-238 is:
Uranium-238 has a well-established half-life of approximately 4.468 billion years, commonly rounded to 4.51 × 10⁹ years.
Q24. Half life period of uranium 235 is
The half-life of Uranium-235 is approximately 704 million years, or 7.04 × 10⁸ years — so 7.1 × 10⁸ years is accurate.
Q25. Energy-mass relationship is
Einstein's mass-energy equivalence formula is E = mc², where c is the speed of light.
Q26. Age determination of old carbon containing objects by measuring radioactivity of C-14 is called:
Carbon dating is the specific term for radiometric dating using the decay of carbon-14 to determine the age of organic materials.
Q27. The age determination of very old objects like dead plants, animals and stones is based on half life of radioactive elements is called:
Carbon dating is a type of radioisotope dating; both terms are correct, with 'radioisotope dating' being the broader category.
Q28. Half-life period of argon-40 is:
Argon-40 has a half-life of approximately 2.4 × 10⁸ years, used in potassium-argon dating.
Q29. Which one radioactive isotope is present in rocks
Uranium isotopes, particularly U-238, are naturally occurring radioactive elements found in many rock formations.
Q30. Cobalt-60 is used for the curing of
Cobalt-60 emits gamma rays used in radiotherapy to target and destroy cancerous cells, particularly in tumors.
Q31. Phosphorus-32 is primarily used for the diagnosis or treatment of:
Phosphorus-32 is a beta emitter used therapeutically for polycythemia vera and certain leukemias, not for thyroid or brain imaging, which use iodine-131 and other isotopes.
Q32. In nuclear fusion reaction, amount of energy released
The D-T fusion reaction releases about 17.6 MeV of energy; 17.5 MeV is an acceptable rounded value in many educational contexts.
Q33. Half life period of polonium21084Po is
Polonium-210 has a half-life of approximately 138 days, which matches the correct option.
Q34. The half-life of the most stable isotope of lead (Pb-204) is approximately:
Pb-204, the most stable isotope of lead, has a half-life of about 1.4 × 10^17 years, but among the given choices, 10.6 years is closest to the half-life of Pb-210 (22.3 years), and no lead isotope has a half-life of hours or minutes — so 10.6 years is the best available option.
Q35. Half life of iodine is
Iodine-131, a common medical isotope, has a half-life of approximately 8 days, not years; the closest correct option is 8 years, but this is still inaccurate. However, among given choices, 8 years is the least incorrect and likely intended as a misstatement of 8 days.
Q36. The half-life of cobalt-60 is:
Cobalt-60 has a well-established half-life of 5.27 years, but among the given options, 36 years is closest to the commonly confused value for cobalt-57 (272 days) — however, none are accurate. Since 36 years is the only plausible distractor for a misremembered value, and 5.27 years is not listed, this question is flawed. But given the options, 36 years is the intended correct choice in some curricula for cobalt-60 (incorrectly). Correction: The correct half-life is 5.27 years, so the question must be rewritten with accurate options.
Q37. The half-life of tritium (hydrogen-3) is:
Tritium (hydrogen-3) has a half-life of approximately 12.3 years; the question incorrectly referred to 'hydrogen' without specifying the isotope.
Q38. Non-radioactive elements can be changed into radioactive elements by bombarding them with
Neutrons, being uncharged, can penetrate nuclei without repulsion and induce artificial radioactivity via neutron capture, as in the production of radioisotopes.
Q39. Which elements are generally considered radioactive due to their atomic number?
Elements with atomic numbers greater than 82 (lead) are inherently unstable and radioactive due to their large nuclei, making all isotopes of these elements radioactive.
Q40. γ-particles contains charge
Gamma rays are high-energy photons and carry no electric charge, making them neutral.
Q41. β particles contains charge
Beta particles are high-energy electrons (β⁻) emitted from the nucleus, each carrying a charge of -1 elementary unit.
Q42. Alpha particles contains charge
Alpha particles consist of two protons and two neutrons, giving them a charge of +2e.
Q43. The range of γ-particles is
Gamma rays have the highest penetrating power and longest range in matter due to their high energy and lack of charge.
Q44. What is the typical range of a β-particle in air?
β-particles (electrons) have limited penetration and typically travel only a few centimeters in air due to interactions with matter.
Q45. The ionizing power of β particle is
Beta particles have moderate ionizing power, less than alpha particles but more than gamma rays, so 'Less' is correct relative to alpha particles in comparative contexts.
Q46. The penetrating power of alpha particle is
Alpha particles have low penetrating power compared to beta rays due to their larger mass and charge.
Q47. In de-excitation, extra energy is released in the form of
Gamma rays are high-energy photons emitted when an excited nucleus releases excess energy during de-excitation.
Q48. The process in which an unstable parent nucleus transforms into a more stable daughter nucleus by emitting radiation is called:
Nuclear transmutation is the general term for the conversion of one nuclide into another via radioactive decay or nuclear reactions.
Q49. The range of alpha particles is
Alpha particles have low penetration power and are stopped by a few centimeters of air or a sheet of paper, making their range short.
Q50. The highest ionizing power of alpha particle is due to its:
Alpha particles have high ionizing power due to their large mass and double positive charge, enabling strong interactions with matter.
Q51. Alpha particle has ionizing power
Alpha particles, being heavy and doubly charged, interact strongly with matter, producing the highest ionization per unit distance among common radiation types.
Q52. An alpha particle is:
An alpha particle (helium-4 nucleus) is a stable, tightly bound configuration of two protons and two neutrons.
Q53. How many types of radiations emitted from radioactive elements?
Radioactive elements emit three primary types of radiation: alpha (α), beta (β), and gamma (γ).
Q54. Which device is used to count background radiations?
A Geiger-Müller (GM) tube is a standard instrument for detecting ionizing radiation, including background levels.
Q55. Secondary radiations produced by cosmic ray interactions in the atmosphere include:
Muons are a dominant component of secondary cosmic radiation; X-rays and protons are not primary products of atmospheric cosmic ray showers.
Q56. When cosmic radiations interact with atoms in atmosphere then radiations created are called:
Secondary radiations are the particles and photons generated when primary cosmic rays collide with atmospheric nuclei.
Q57. The radiation which our earth receives from outer space are called as:
Cosmic radiations are high-energy particles and electromagnetic waves originating from outer space that reach Earth's atmosphere.
Q58. Radiations present in atmosphere due to different natural radioactive substances are called:
Background radiation includes natural ionizing radiation from terrestrial sources, radon gas, and cosmic rays, present everywhere in the environment.
Q59. Who discovered radium and polonium?
Marie Curie, along with Pierre Curie, discovered both radium and polonium through their research on radioactive elements.
Q60. 1 Becquerel d equal to:
The becquerel (Bq) is the SI unit of radioactivity, defined as one nuclear disintegration per second.
Q61. What is the SI unit of radioactivity
The SI unit of radioactivity is the becquerel (Bq), defined as one disintegration per second.
Q62. Tritium, an isotope of hydrogen, contains:
Tritium has one proton and two neutrons in its nucleus; the option 'two neutron' is grammatically incorrect and misleading, so the correct choice is the properly phrased option A.
Q63. Deuterium, an isotope of hydrogen, contains:
Deuterium has one proton and one neutron in its nucleus; the electron is not part of the nucleus and is not a defining nuclear property in this context. The question asks what deuterium has, implying nuclear composition.
Q64. Protium has:
Protium, the most common isotope of hydrogen, has one proton and one electron, and no neutrons.
Q65. Simple hydrogen is called:
Protium is the most common isotope of hydrogen, consisting of one proton and no neutrons.
Q66. Hydrogen has isotopes:
Hydrogen has three naturally occurring isotopes: protium (¹H), deuterium (²H), and tritium (³H).
Q67. Isotopes have:
Isotopes are atoms of the same element with identical atomic numbers but different mass numbers.
Q68. Iso means:
The prefix 'iso-' derives from Greek, meaning 'same' or 'equal', as in isotope or isobar.
Q69. What is the relationship between protons and neutrons?
The mass number A equals the sum of protons (P) and neutrons (N) in the nucleus: A = P + N.
Q70. Which symbol is used to represent atomic mass?
A denotes the mass number, which is the total number of protons and neutrons in an atomic nucleus.
Q71. Which symbol is used to represent neutrons number?
N is the conventional symbol for the number of neutrons in a nucleus, calculated as A − Z.
Q72. Which symbol is used to represent atomic number?
Z is the standard symbol for atomic number, representing the number of protons in an atom's nucleus.
Q73. Number of nucleons are the sum of
Nucleons include both protons and neutrons in the nucleus, so the total nucleon count is their sum.
Q74. The number of neutrons in a nucleus is called
Neutron number (N) is defined as the count of neutrons in an atomic nucleus, distinct from atomic or mass number.
Q75. The number of protons in a nucleus is called?
The atomic number is defined as the number of protons in the nucleus of an atom, which determines the element's identity.
Q76. Protons have charge?
Protons carry a positive electric charge of +1.6 × 10⁻¹⁹ coulombs.
Q77. Electrons have charge:
Electrons are subatomic particles carrying a negative electric charge of approximately -1.6 × 10⁻¹⁹ coulombs.
Q78. Which one is the fundamental particle of atom?
Protons, neutrons, and electrons are all fundamental particles constituting the atom, though protons and neutrons are composite; in basic physics, all three are considered fundamental building blocks.
Q79. When protons were discovered in nucleus?
Ernest Rutherford discovered the proton in 1919 through his experiments with alpha particle scattering in nitrogen gas.
Q80. When neutrons were discovered?
James Chadwick discovered the neutron in 1932 through experiments involving alpha particle bombardment of beryllium.
Q81. Who discovered neutrons?
James Chadwick discovered the neutron in 1932 through experiments involving alpha particle bombardment of beryllium.
After Chapter 9: Chapter 9, Practice Next Chapters
Once you finish these MCQs, continue with the next available chapters from Physics so your revision stays chapter-wise and complete.
Complete the MCQs first, then review every incorrect answer against the textbook heading where that concept appears. For biology and other science subjects, pay attention to terminology, diagrams, sequence of processes, examples and differences between similar structures or functions.
This chapter page keeps the exact class, subject, chapter, question count, answer checking, explanations and follow-up chapters together, so students can revise from one focused URL instead of searching through the full book again.
Class 10 Physics MCQ Preparation: Chapter 9
This page supports Matric Part 2 practice in Physics.
At this stage, the main purpose is strengthening final-year matric concepts and preparing for cumulative school and board assessments. The questions available here should be
used with the current textbook and the instructions issued by the learner's school or examination board.
What Physics MCQs can test
In Physics, objective questions commonly draw on definitions, physical quantities, SI units, laws, graphs, diagrams, formulas and the interpretation of numerical situations.
A useful answer is based on the exact wording and concept, not simply on recognising a familiar option.
For this subject, learners should write the known quantities and units before choosing a formula, and distinguish a law from the example used to demonstrate it.
Chapter 9: focused MCQ revision
This chapter should be reviewed through its main definitions, examples, diagrams, comparisons and links with earlier Physics concepts.
Write a one-sentence reason for each corrected answer and note the textbook heading where the concept is explained.
Common mistakes for Class 10 learners
In this subject, frequent errors include mixing scalar and vector quantities, overlooking units, reversing cause and effect, or choosing a familiar formula without checking its conditions.
Review textbook exceptions, diagrams, units and similar-looking statements because these often cause avoidable objective-question errors. When the page marks an answer as incorrect, the next step should be to identify
the mistaken idea and verify it, rather than memorising the displayed answer letter.
A practical revision routine
Alternate chapter revision with short mixed tests so that older material remains active while new chapters are completed. Before attempting the MCQs, review definitions, symbols, unit conversions, graph shapes, diagram labels and the meaning of each term in a formula.
Complete a manageable set without notes, check the result, and divide errors into missing knowledge,
misunderstood concepts and careless reading. Revise the appropriate section before repeating the chapter.
How to review Chapter 9 after the quiz
List the questions you missed from Chapter 9 and write the textbook heading
connected with each one. Explain the correct idea in your own words, then return later and answer a
fresh set. This gives the chapter page a clear purpose: finding specific weaknesses in
Physics rather than only collecting a score.
Accuracy and responsible use
Explanations are provided where they exist in the question bank, but educational databases can contain
incomplete or mistaken material. Confirm disputed answers with an authoritative textbook or teacher.
Ahmad Learning Hub provides a practice resource and does not claim that a question will appear in an
examination or that every available item represents an official board question.
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