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Q1Science·Energy, Nuclear and Material SciencePYQ 2024
With reference to radioisotope thermoelectric generators (RTGs), consider the following statements:
1. RTGs are miniature fission reactors.
2. RTGs are used for powering the onboard systems of spacecrafts.
3. RTGs can use Plutonium-238, which is a by-product of weapons development.
Which of the statements given above are correct?
- A1 and 2 only
- B2 and 3 onlyCorrect
- C1 and 3 only
- D1, 2 and 3
Explanation
Correct. RTGs rely on radioactive decay (not fission) to generate electricity for spacecraft, and they commonly use Plutonium-238 originally produced in weapons-grade reactor programmes.
Q2Science·Energy, Nuclear and Material SciencePYQ 2023
Consider the following statements:
Statement-I: India, despite having uranium deposits, depends on coal for most of its electricity production.
Statement-II: Uranium, enriched to the extent of at least 60%, is required for the production of electricity.
Which one of the following is correct in respect of the above statements?
- ABoth Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement-I
- BBoth Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I
- CStatement-I is correct but Statement-II is not correctCorrect
- DStatement-I is not correct but Statement-II is correct
Explanation
Correct. India does rely on coal for the bulk of its electricity despite having uranium reserves. However, nuclear power reactors use low-enriched uranium (about 3-5% U-235), not 60%.
Q3Science·Energy, Nuclear and Material SciencePYQ 2016
India is an important member of the 'International Thermonuclear Experimental Reactor'. If this experiment succeeds, what is the immediate advantage for India?
- AIt can use thorium in place of uranium for power generation
- BIt can attain a global role in satellite navigation
- CIt can drastically improve the efficiency of its fission reactors in power generation
- DIt can build fusion reactors for power generationCorrect
Explanation
Correct. ITER is an international project to demonstrate the feasibility of nuclear fusion as a large-scale energy source; success would enable India to build fusion reactors for power generation.
Q4Science·Energy, Nuclear and Material SciencePYQ 2013
The known forces of nature can be divided into four classes, viz., gravity, electromagnetism, weak nuclear force and strong nuclear force. With reference to them, which one of the following statements is not correct?
- AGravity is the strongest of the fourCorrect
- BElectromagnetism acts only on particles with an electric charge
- CWeak nuclear force causes radioactivity
- DStrong nuclear force holds protons and neutrons inside the nucleus of an atom
Explanation
Correct. Gravity is actually the weakest of the four fundamental forces, not the strongest. The strong nuclear force is the strongest.
Q5Science·Energy, Nuclear and Material SciencePYQ 2013
The efforts to detect the existence of Higgs boson particle have become frequent news in the recent past. What is/are the importance of discovering this particle?
1. It will enable us to understand as to why elementary particles have mass.
2. It will enable us in the near future to develop the technology of transferring matter from one point to another without traversing the physical space between them.
3. It will enable us to create better fuels for nuclear fission.
Select the correct answer using the codes given below.
- A1 onlyCorrect
- B2 and 3 only
- C1 and 3 only
- D1, 2 and 3
Explanation
Correct. The Higgs boson is associated with the Higgs field, which gives elementary particles their mass. Statements 2 and 3 are science fiction with no basis in the Standard Model.
Q6Science·Energy, Nuclear and Material SciencePYQ 2011
The function of heavy water in a nuclear reactor is to:
- ASlow down the speed of neutronsCorrect
- BIncrease the speed of neutrons
- CCool down the reactor
- DStop the nuclear reaction
Explanation
Correct. Heavy water (D₂O) serves as a moderator in nuclear reactors, slowing down fast neutrons to thermal energies so they can sustain the fission chain reaction.
Q7Science·Energy, Nuclear and Material SciencePYQ 2007
Four wires of same material and of dimensions as under are stretched by a load of same magnitude separately. Which one of them will be elongated maximum?
- AWire of 1 m length and 2 mm diameter
- BWire of 2 m length and 2 mm diameter
- CWire of 3 m length and 1.5 mm diameterCorrect
- DWire of 1 m length and 1 mm diameter
Explanation
Correct. Elongation = FL/(AY). This wire has the highest ratio of length to cross-sectional area (3 m / π(0.75 mm)²), producing maximum elongation.
Q8Science·Energy, Nuclear and Material SciencePYQ 1998
Match the names of outstanding Indian scientists given in List I with the area of their specialised work given in List II:
List I:
I. Dr. Raja Ramanna
II. Dr. M.S. Swaminathan
III. Prof. U.R. Rao
IV. Prof. Meghnad Saha
List II:
A. Plant Chemistry
B. Nuclear Physics
C. Thermodynamics and Astrophysics
D. Space Research
E. Agricultural Sciences
Select the correct answer using the codes given below:
- AI-B, II-E, III-D, IV-CCorrect
- BI-B, II-A, III-D, IV-C
- CI-C, II-E, III-B, IV-A
- DI-C, II-A, III-D, IV-B
Explanation
Correct. Raja Ramanna was a nuclear physicist; M.S. Swaminathan is the father of India's Green Revolution (agricultural sciences); U.R. Rao led India's space programme; Meghnad Saha is known for the Saha ionisation equation in thermodynamics and astrophysics.
Q9Science·Energy, Nuclear and Material SciencePYQ 1998
Which one of the following statements correctly describes the difference between a nuclear reactor and an atomic bomb?
- ANo chain reaction takes place in a nuclear reactor while in the atomic bomb there is a chain reaction
- BThe chain reaction in a nuclear reactor is controlledCorrect
- CThe chain reaction in a nuclear reactor is not controlled
- DNo chain reaction takes place in an atomic bomb while it takes place in a nuclear reactor
Explanation
Correct. In a nuclear reactor the chain reaction is controlled using moderators and control rods to sustain a steady energy output, whereas in an atomic bomb the chain reaction is uncontrolled and explosive.
Q10Science·Energy, Nuclear and Material Science
With reference to 'perovskite solar cells', consider the following statements:
1. They use a class of materials with a crystal structure similar to calcium titanium oxide.
2. They have shown rapid improvement in efficiency in recent years.
3. They are already more commercially widespread than silicon solar cells.
Which of the statements given above is/are correct?
- A1 only
- B1 and 2 onlyCorrect
- C2 and 3 only
- D1, 2 and 3
Explanation
Correct. Perovskite solar cells use the ABX₃ crystal structure and have seen dramatic efficiency improvements. Statement 3 is wrong; silicon cells still dominate the commercial market, while perovskites face stability and scaling challenges.
Q11Science·Energy, Nuclear and Material Science
Which of the following correctly describes the phenomenon of 'doping' in semiconductors?
- AAdding impurity atoms to a pure semiconductor to modify its electrical conductivityCorrect
- BCoating a semiconductor with a metallic layer for corrosion resistance
- CExposing a semiconductor to high temperatures to make it an insulator
- DRemoving impurities from a semiconductor to make it perfectly non-conducting
Explanation
Correct. Doping is the deliberate introduction of impurity atoms (like phosphorus or boron) into a pure semiconductor crystal to increase the number of free charge carriers and modify conductivity (n-type or p-type).
Q12Science·Energy, Nuclear and Material Science
In the context of radioactive decay, what happens during 'beta decay'?
- AA neutron is converted into a proton and an electron (beta particle) is emittedCorrect
- BA helium nucleus is emitted from the parent atom
- CA high-energy photon is emitted from the nucleus
- DThe atom absorbs an external electron into the nucleus
Explanation
Correct. In beta-minus decay, a neutron in the nucleus is converted into a proton, and an electron (beta particle) along with an antineutrino is emitted.