ICSE Class 10

General instructions: Answer all questions. Marks are shown in brackets [ ].

Objective

1. 1.
   Why should a radioactive substance not be touched by hand?

   1. A. It can cause severe burns, genetic damage, or cancer due to harmful radiations.
   2. B. It may explode or catch fire upon contact with skin.
   3. C. It can dissolve the skin and enter the bloodstream directly.
   4. D. It becomes unstable and releases toxic gases when touched.
   [1]
2. 2.
   Which of the following sets of safety precautions should you take while handling radioactive substances?

   1. A. Use protective clothing and gloves, handle substances with tongs or remote tools, and store materials in lead-lined containers.
   2. B. Wear ordinary lab coats, handle substances with bare hands, and store materials in plastic containers.
   3. C. Use sunglasses for eye protection, handle substances with metal tools, and store materials in wooden boxes.
   4. D. Wear a face mask, handle substances with cloth gloves, and store materials in glass jars.
   [1]
3. 3.
   What are mirror isobars?

   1. A. Isobars where the number of protons and neutrons in the nucleus are interchanged, e.g., $^{23}_{11}\mathrm{Na}$ and $^{23}_{12}\mathrm{Mg}$.
   2. B. Isotopes of the same element with identical mass numbers but different atomic numbers.
   3. C. Atoms with the same number of neutrons but different numbers of protons.
   4. D. Elements with identical atomic numbers but different mass numbers, e.g., $^{12}_{6}\mathrm{C}$ and $^{14}_{6}\mathrm{C}$.
   [1]
4. 4.
   Which property correctly distinguishes alpha particles from gamma radiations?

   1. A. Alpha particles are helium nuclei and deflected by electric fields; gamma rays are uncharged electromagnetic waves.
   2. B. Alpha particles are electromagnetic waves; gamma rays are charged particles.
   3. C. Alpha particles have no mass; gamma rays are heavy nuclei.
   4. D. Alpha particles penetrate deeply; gamma rays are stopped by paper.
   [1]
5. 5.
   Which of the following best describes the tracer technique?

   1. A. Using a chemical dye to track fluid flow in pipes
   2. B. Adding a small quantity of a radio-isotope to study a phenomenon
   3. C. Measuring temperature changes in a substance over time
   4. D. Using X-rays to detect internal structures in materials
   [1]
6. 6.
   The nucleus of a hydrogen atom can be represented by this symbol: ¹₁H (i) The symbol shows that the nucleus consists of

   1. A. 1 proton and 1 neutron
   2. B. 1 proton only
   3. C. 1 neutron only
   4. D. 1 neutron and 1 electron
   [2]
7. 7.
   Which of the following correctly represents the nuclear fusion reaction involving two deuterium nuclei and the energy released in the process?

   1. A. $^{2}_{1}\text{H} + ^{2}_{1}\text{H} \rightarrow ^{3}_{2}\text{He} + ^{0}_{1}n + 3.3 \text{ MeV}$, followed by $^{3}_{2}\text{He} + ^{2}_{1}\text{H} \rightarrow ^{4}_{2}\text{He} + ^{1}_{1}\text{H} + 18.3 \text{ MeV}$
   2. B. $^{2}_{1}\text{H} + ^{2}_{1}\text{H} \rightarrow ^{4}_{2}\text{He} + 24.6 \text{ MeV}$ (single-step reaction with total energy release)
   3. C. $^{2}_{1}\text{H} + ^{2}_{1}\text{H} \rightarrow ^{3}_{1}\text{H} + ^{1}_{1}\text{H} + 4.0 \text{ MeV}$ (tritium and proton formation only)
   4. D. $^{2}_{1}\text{H} + ^{2}_{1}\text{H} \rightarrow ^{3}_{2}\text{He} + ^{0}_{1}n - 3.3 \text{ MeV}$ (energy absorbed instead of released)
   [1]
8. 8.
   How do alpha particles behave in electric and magnetic fields, and why is their deflection less than that of beta particles?

   1. A. Alpha particles are deflected by electric and magnetic fields due to their positive charge, and their deflection is less because they are much heavier.
   2. B. Alpha particles are not deflected by electric or magnetic fields because they carry no charge.
   3. C. Alpha particles are deflected more than beta particles because they have a higher charge-to-mass ratio.
   4. D. Alpha particles are deflected by electric fields but not magnetic fields, and their deflection is less due to lower velocity.
   [1]
9. 9.
   In the fusion reaction: $$^{2}\mathrm{H} + ^{2}\mathrm{H} \longrightarrow ^{4}\mathrm{He} + x$$, what does $$x$$ represent?

   1. A. A neutron
   2. B. A proton
   3. C. Energy produced by the fusion
   4. D. Another helium nucleus
   [1]
10. 10.
    What is the primary purpose of carbon-14 dating?

    1. A. To measure the carbon content in living organisms.
    2. B. To determine the age of dead organic matter by measuring carbon-14 decay.
    3. C. To detect the presence of carbon-14 in inorganic materials.
    4. D. To accelerate the decay of carbon-14 for industrial use.
    [1]
11. 11.
    Compare the ionising power of α, β and γ radiations. Which of the following statements correctly describes their relative ionising abilities?

    1. A. α-particles have the highest ionising power, about 100 times that of β-particles and 10,000 times that of γ-radiation.
    2. B. β-particles have the highest ionising power, about 100 times that of α-particles and 10,000 times that of γ-radiation.
    3. C. γ-radiation has the highest ionising power, about 100 times that of α-particles and 10,000 times that of β-particles.
    4. D. α, β, and γ radiations have nearly equal ionising power, with minor differences due to their charges.
    [1]
12. 12.
    Name the atoms of a substance having the same atomic number, but different mass numbers. Which of the following correctly identifies such atoms, provides an example, and describes their structural difference?

    1. A. Isobars. Example: Carbon-14 and Nitrogen-14. They differ in the number of protons.
    2. B. Isotopes. Example: Uranium-235 and Uranium-238. They differ in the number of neutrons in the nucleus.
    3. C. Isomers. Example: Glucose and Fructose. They differ in the arrangement of atoms.
    4. D. Isotones. Example: Carbon-12 and Oxygen-16. They differ in the number of protons but have the same neutrons.
    [1]
13. 13.
    What is the concept of radio isotopes, and which of the following correctly represents two of their medical uses?

    1. A. Radio isotopes are stable isotopes of elements with atomic number Z < 82, used in X-ray imaging and chemotherapy.
    2. B. Radio isotopes are unstable isotopes of elements with atomic number Z < 82 that emit radiation, used in radiotherapy (e.g., cobalt-60 for cancer) and diagnosis (e.g., radio-iodine as a tracer).
    3. C. Radio isotopes are synthetic elements with atomic number Z > 82, used in MRI scans and ultrasound imaging.
    4. D. Radio isotopes are isotopes of heavy metals, used primarily in sterilizing surgical instruments and disinfecting wounds.
    [1]
14. 14.
    Which of the following correctly describes the production methods of X-rays and γ-rays?

    1. A. X-rays are produced by fast electrons striking a low atomic weight metal; γ-rays are produced by chemical reactions.
    2. B. X-rays are produced when fast moving electrons strike a metal of high atomic weight and high melting point; γ-rays are produced from nuclei of substances either by artificial or natural disintegrations.
    3. C. X-rays are produced by nuclear fission; γ-rays are produced by electron bombardment of gases.
    4. D. X-rays and γ-rays are both produced by heating metals to extremely high temperatures.
    [1]
15. 15.
    During the emission of a beta particle from a radioactive nucleus, which of the following remains the same?

    1. A. Atomic number
    2. B. Mass number
    3. C. Number of neutrons
    4. D. Number of protons
    [1]
16. 16.
    A thorium isotope ${}^{223}\mathrm{Th}$ undergoes an α-decay and changes into radium. What are the atomic number and mass number of the radium produced?

    1. A. Atomic number 88, mass number 219
    2. B. Atomic number 90, mass number 223
    3. C. Atomic number 86, mass number 215
    4. D. Atomic number 92, mass number 227
    [1]
17. 17.
    When four hydrogen nuclei combine to form a helium nucleus in the interior of the sun, the loss in mass is 0.0265 a.m.u. How much energy is released?

    1. A. 2.47 MeV
    2. B. 24.7 MeV
    3. C. 247 MeV
    4. D. 0.247 MeV
    [1]
18. 18.
    How much energy is released when a mass of 1 g is completely converted into energy? (Given, velocity of light c = 3 × 10⁸ m s⁻¹.)

    1. A. 3 × 10¹⁰ J
    2. B. 9 × 10¹³ J
    3. C. 3 × 10¹³ J
    4. D. 9 × 10¹⁰ J
    [1]
19. 19.
    Why are gamma rays emitted only in nuclear processes and not in orbital electron transitions?

    1. A. Gamma rays have energy in the eV range, matching electron transitions.
    2. B. Gamma rays have energy in the MeV range, which occurs only in nuclear processes.
    3. C. Gamma rays are produced by electron transitions in outer orbits.
    4. D. Gamma rays are too weak to be produced in nuclear processes.
    [1]
20. 20.
    When Uranium nucleus ²³⁸₉₂U decays to Lead ²⁰⁶₈₂Pb, how many alpha and beta particles are emitted?

    1. A. 6 alpha, 8 beta
    2. B. 8 alpha, 6 beta
    3. C. 7 alpha, 4 beta
    4. D. 5 alpha, 10 beta
    [1]