Nuclear Physics

11. Large Hadron Collider was in news recently for doing some scientific r

Large Hadron Collider was in news recently for doing some scientific research to prove the presence of an elementary particle. The scientist who predicted this particle in 1964 has been awarded Nobel Prize in 2013. What is this discovery ?

[amp_mcq option1=”Particles known as quarks having mass” option2=”Origin of Universe timings” option3=”Bigg’s Bosons or God Particles explaining why fundamental particles have mass” option4=”None of the above” correct=”option3″]

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The question describes the search and discovery of the Higgs boson at the Large Hadron Collider (LHC) at CERN, which was heavily in the news, leading to the 2013 Nobel Prize in Physics awarded to François Englert and Peter Higgs who had theorized its existence in 1964.
The Higgs boson is an elementary particle associated with the Higgs field. This field is thought to be present throughout the universe, and interactions with it give other fundamental particles (like quarks and leptons) their mass. It is often popularly referred to as the “God particle”.
– Quarks are fundamental particles that are components of protons and neutrons; they do have mass, but the Higgs mechanism explains *why* they have mass, not just that they do.
– The origin of the universe timings is related to cosmology and the Big Bang theory, not the Higgs boson discovery.
– The LHC is the world’s largest and most powerful particle accelerator, used to collide beams of protons or heavy ions at high energies to study fundamental particles and forces.

12. Consider the following statements: 1. Discovery of Higgs boson of wh

Consider the following statements:

  • 1. Discovery of Higgs boson of which scientists are almost certain, may discard Einstein’s special theory of relativity.
  • 2. Probable discovery of a particle which moves faster than light may prove Stephen Hawking wrong.
  • 3. Probable discovery of a particle that moves faster than light may go against Einstein’s special theory of relativity.

Which of the statements given above is/are correct?

[amp_mcq option1=”1 and 2″ option2=”1 only” option3=”3 only” option4=”1 and 3″ correct=”option3″]

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Statement 1: The discovery of the Higgs boson is a cornerstone of the Standard Model of particle physics and is entirely consistent with Einstein’s special theory of relativity. It explains how fundamental particles acquire mass through their interaction with the Higgs field, without discarding special relativity. This statement is incorrect. Statement 2: A particle moving faster than light (superluminal particle) would indeed challenge fundamental physics principles, but stating it would specifically prove Stephen Hawking wrong is not accurate or the primary consequence. Hawking’s work, while profound, is not singularly contingent on the non-existence of superluminal particles in a way that this discovery would directly falsify his main theories. This statement is vague and likely incorrect. Statement 3: Einstein’s special theory of relativity posits that the speed of light in a vacuum is the maximum speed limit for any information or energy transfer. The probable discovery of a particle that moves faster than light would directly contradict this fundamental postulate of special relativity. This statement is correct.
Special relativity sets the speed of light as the ultimate speed limit in the universe. Any particle exceeding this speed would violate its principles, particularly causality.
While there have been discussions and theoretical explorations of possibilities like wormholes or warp drives that might allow effective faster-than-light travel in space-time (potentially consistent with General Relativity under specific, theoretical conditions), the existence of a fundamental particle that inherently travels faster than light in flat space-time is incompatible with Special Relativity.

13. In the recent past, a fundamental particle has been claimed to be expe

In the recent past, a fundamental particle has been claimed to be experimentally observed, at a European Laboratory in Geneva, to travel at a speed greater than that of light in vacuum. The name of the particle is

[amp_mcq option1=”electron” option2=”positron” option3=”neutron” option4=”neutrino” correct=”option4″]

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UPSC CAPF – 2012
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In 2011, the OPERA experiment at the Gran Sasso National Laboratory in Italy (using neutrinos from CERN in Geneva) reported observations suggesting that neutrinos might travel faster than the speed of light in vacuum. This finding caused significant scientific excitement and skepticism.
The particle involved in the experiment claiming superluminal speed was the neutrino. The results were later attributed to experimental errors, specifically a faulty cable connection in the GPS timing system and an oscillator issue, and the initial claim was retracted.
According to Einstein’s theory of special relativity, nothing can travel faster than the speed of light in vacuum (c). The OPERA result, if confirmed, would have fundamentally challenged this principle. Subsequent, more precise experiments confirmed that neutrinos do not travel faster than light.

14. The first large research reactor of India that uses U-233 as fuel is

The first large research reactor of India that uses U-233 as fuel is

[amp_mcq option1=”ZERLINA” option2=”PURNIMA” option3=”DHRUVA” option4=”KAMINI” correct=”option4″]

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UPSC CAPF – 2011
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KAMINI (Kalpakkam Mini Reactor) is a research reactor located at the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam. It is the first reactor in the world that uses Uranium-233 (U-233) as fuel. While its power output is low (30 kWt), making the term “large” somewhat inaccurate compared to reactors like DHRUVA (100 MWt), it is an operational research reactor specifically designed to study U-233 fuel, which is key to India’s thorium fuel cycle program. ZERLINA and PURNIMA-II also used U-233 but were zero or very low power experimental assemblies used for specific lattice studies rather than continuous research operation. DHRUVA is India’s largest research reactor but uses natural uranium.
KAMINI is the only operational reactor in India listed that uses U-233 fuel. It is specifically designed for research purposes related to the thorium fuel cycle.
India has pursued a three-stage nuclear power program aimed at utilizing its vast thorium reserves. The thorium cycle involves breeding U-233 from thorium. KAMINI plays a role in studying the characteristics of U-233 fuel. It achieved criticality in 1996.

15. Which one of the following pairs of rays is *not* electromagnetic in n

Which one of the following pairs of rays is *not* electromagnetic in nature ?

[amp_mcq option1=”X-rays and cathode rays” option2=”Gamma rays and X-rays” option3=”Alpha rays and beta rays” option4=”Beta rays and gamma rays” correct=”option3″]

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UPSC CAPF – 2010
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Alpha rays and beta rays are *not* electromagnetic in nature.
– Electromagnetic (EM) radiation consists of waves of oscillating electric and magnetic fields that travel at the speed of light. Examples include radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
– X-rays and gamma rays are high-energy forms of electromagnetic radiation.
– Alpha rays are streams of alpha particles, which are helium nuclei (2 protons, 2 neutrons). They are massive particles with a positive charge.
– Beta rays are streams of beta particles, which are high-energy electrons (β⁻ decay) or positrons (β⁺ decay). They are particles with a negative or positive charge.
– Cathode rays are streams of electrons, typically observed in vacuum tubes. They are also particles.
Alpha, beta, and cathode rays are beams of charged particles, subject to electric and magnetic fields in a way that EM waves are not (EM waves are only affected by changes in the medium they travel through or by strong gravitational fields in extreme cases).

16. Nuclear energy is generated by

Nuclear energy is generated by

[amp_mcq option1=”nuclear fission and its expression was proposed by Einstein.” option2=”nuclear fission and its expression was proposed by Rutherford.” option3=”nuclear fusion and its expression was proposed by Bohr.” option4=”nuclear fusion and its expression was proposed by Heisenberg.” correct=”option1″]

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The correct option is A. Nuclear energy is typically generated through nuclear fission in power plants, and the fundamental principle linking mass and energy, which is the basis of energy release in both fission and fusion, is expressed by Einstein’s famous equation E=mc².
Nuclear power plants primarily utilize nuclear fission of heavy elements like Uranium or Plutonium to produce energy. While nuclear fusion is the source of energy in stars and a potential future energy source on Earth, current commercial nuclear power is based on fission. The relationship between the mass deficit and the energy released in nuclear reactions is described by Albert Einstein’s mass-energy equivalence principle, E=mc².
Nuclear fission is a nuclear reaction in which a heavy nucleus splits into lighter nuclei, releasing a large amount of energy. Nuclear fusion is a reaction in which light nuclei combine to form a heavier nucleus, also releasing energy. Rutherford is known for the discovery of the nucleus and the planetary model of the atom (later refined). Bohr developed a model of the atom explaining atomic spectra. Heisenberg is one of the pioneers of quantum mechanics, known for the uncertainty principle.

17. Rutherford’s alpha-particle ($\alpha$) scattering experiment was respo

Rutherford’s alpha-particle ($\alpha$) scattering experiment was responsible for the discovery of which one of the following ?

[amp_mcq option1=”Electron” option2=”Proton” option3=”Atomic Nucleus” option4=”Neutron” correct=”option3″]

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Rutherford’s alpha-particle scattering experiment, also known as the Gold Foil experiment, involved firing alpha particles at a thin sheet of gold foil. Most of the alpha particles passed straight through the foil, some were deflected at small angles, and a very small number were deflected at large angles or even bounced back. These observations led Rutherford to propose the existence of a small, dense, positively charged core at the center of the atom, which he called the nucleus. This experiment was a crucial step in understanding the structure of the atom, replacing Thomson’s plum pudding model.
The key finding was that the atom’s positive charge and most of its mass are concentrated in a tiny volume at the center, causing the rare but significant deflections of the positively charged alpha particles.
Electrons were discovered by J.J. Thomson using cathode ray tubes. Protons were later identified as the positively charged particles within the nucleus. Neutrons were discovered by James Chadwick in 1932, much later than Rutherford’s experiment (conducted in 1909-1911, model proposed in 1911).

18. Which one of the following element’s isotope is used in the treatment

Which one of the following element’s isotope is used in the treatment of cancer ?

[amp_mcq option1=”Uranium” option2=”Cobalt” option3=”Sodium” option4=”Iodine” correct=”option2″]

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UPSC NDA-2 – 2020
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Cobalt-60 is a widely used radioactive isotope in cancer treatment, specifically in external beam radiotherapy (using a Cobalt therapy machine) due to its emission of high-energy gamma rays which are effective in killing cancer cells.
– Radioisotopes like Cobalt-60 are used in cancer treatment (radiotherapy) to damage the DNA of cancer cells and prevent them from growing and dividing.
– Iodine-131 is used specifically in the treatment of thyroid cancer and hyperthyroidism.
– Uranium is primarily known for its use in nuclear power and weapons, not medical treatment in this context.
– Sodium isotopes are often used as tracers but not standard therapeutic agents for cancer.
Apart from Cobalt-60 and Iodine-131, other radioisotopes used in cancer treatment include Iridium-192 (brachytherapy), Cesium-137 (brachytherapy), Gold-198 (brachytherapy), and Phosphorus-32 (for certain blood disorders affecting bone marrow). Brachytherapy involves placing the radioactive source directly inside or next to the tumour.

19. The ionization energy of hydrogen atom in the ground state is

The ionization energy of hydrogen atom in the ground state is

[amp_mcq option1=”13.6 MeV” option2=”13.6 eV” option3=”13.6 Joule” option4=”Zero” correct=”option2″]

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UPSC NDA-2 – 2017
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The ionization energy of a hydrogen atom is the minimum energy required to remove the electron from the ground state (n=1) and take it to the ionization limit (n=infinity).
The energy of an electron in the n-th energy level of a hydrogen atom is given by E_n = -13.6/n² eV. In the ground state (n=1), the energy is E₁ = -13.6/1² = -13.6 eV. At the ionization limit (n=infinity), the energy is E_infinity = -13.6/infinity² = 0 eV. The ionization energy is the difference between these energies: Ionization Energy = E_infinity – E₁ = 0 – (-13.6 eV) = +13.6 eV.
MeV (Mega electron Volt) and Joule are also units of energy, but 13.6 eV is the standard and correct value for the hydrogen atom’s ionization energy. 1 eV is approximately 1.602 x 10⁻¹⁹ J. 1 MeV is 10⁶ eV. 13.6 MeV is an extremely large amount of energy in this context. Zero ionization energy would mean no energy is required to remove the electron, which is incorrect for a bound electron.

20. Which one of the following statements is correct?

Which one of the following statements is correct?

[amp_mcq option1=”Rutherford’s alpha-particle scattering experiment led to the discovery of electron.” option2=”J J Thomson suggested that the nucleus of an atom contains protons.” option3=”The atomic number of an element is the same as the number of protons in the nucleus of its atom.” option4=”The mass number of an atom is equal to the number of electrons in its shells.” correct=”option3″]

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UPSC NDA-2 – 2015
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Let’s analyze each statement:
A) Rutherford’s alpha-particle scattering experiment led to the discovery of the atomic *nucleus*, not the electron. The electron was discovered by J.J. Thomson through his cathode ray experiments.
B) J J Thomson proposed the ‘plum pudding’ model, where electrons were embedded in a diffuse positive charge. Rutherford, based on his experiment, proposed the nuclear model with a central positive nucleus containing protons and neutrons (neutrons were discovered later by Chadwick).
C) The atomic number (Z) of an element is defined as the number of protons in the nucleus of an atom of that element. This statement is correct.
D) The mass number (A) of an atom is the total number of protons and neutrons in the nucleus (A = Z + N). It is not equal to the number of electrons in its shells (unless the atom is neutral, but even then, mass number is protons + neutrons, not just electrons).
The atomic number of an element is a fundamental property that uniquely identifies it and is equal to the number of protons in the nucleus.
Rutherford’s experiment provided evidence for a small, dense, positively charged nucleus. J.J. Thomson’s model was disproven by Rutherford’s findings. The number of electrons in a neutral atom is equal to the number of protons (the atomic number), but this is not the definition of mass number. The mass number is the sum of protons and neutrons, which account for most of the atom’s mass.
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