Nuclear energy is generated by
- (a)nuclear fission and its expression was proposed by Einstein.
- (b)nuclear fission and its expression was proposed by Rutherford.
- (c)nuclear fusion and its expression was proposed by Bohr.
- (d)nuclear fusion and its expression was proposed by Heisenberg.
Correct — A, nuclear fission and its expression was proposed by Einstein. The nuclear energy released in reactors and atom bombs comes from nuclear fission — the splitting of a heavy nucleus (such as uranium-235) into lighter nuclei, which releases a large amount of energy. The 'expression' for that energy is Einstein's mass-energy equivalence, E = mc², which relates the mass lost in the reaction to the energy set free. So the correct pairing is fission with Einstein.
- (b)nuclear fission and its expression was proposed by Rutherford. — The process (fission) is right, but the expression E = mc² was given by Einstein, not Rutherford. Rutherford is known for discovering the nucleus and the first artificial nuclear transmutation, not for the mass-energy relation.
- (c)nuclear fusion and its expression was proposed by Bohr. — The mass-energy relation was proposed by Einstein, not Bohr (who gave the model of the atom with electrons in stable orbits). Fusion does release nuclear energy in stars, but the expression is still Einstein's.
- (d)nuclear fusion and its expression was proposed by Heisenberg. — Again the expression E = mc² is Einstein's, not Heisenberg's (who is known for the uncertainty principle), so this pairing is wrong on the named scientist.
Nuclear energy is the energy released when the nucleus of an atom is rearranged, either by fission (splitting a heavy nucleus) or fusion (joining light nuclei). In either case a small amount of mass is converted into a large amount of energy according to Einstein's equation E = mc². Nuclear reactors and the first atomic bombs generate their energy by controlled and uncontrolled fission of heavy nuclei such as uranium and plutonium.
Two things must both be correct: the process and the scientist who gave the energy 'expression'. Reactors generate energy by fission, and the energy expression E = mc² is Einstein's. Only option (a) gets both right; the others pair the wrong scientist with the process.
- Nuclear fission is the splitting of a heavy nucleus (for example uranium-235) into lighter nuclei, releasing large energy.
- The energy released follows Einstein's mass-energy relation, E = mc².
- Nuclear reactors and atomic bombs generate energy by fission (controlled and uncontrolled respectively).
- Nuclear fusion (joining light nuclei) powers the Sun and stars and also obeys E = mc².
- Pairing fission or fusion with the wrong scientist — the energy expression E = mc² is Einstein's.
- Assuming reactors run on fusion; commercial nuclear reactors generate energy by fission.
Asked as a two-part pairing — match the energy-generating process (fission) with the scientist behind the energy expression (Einstein).
The difference between a nuclear reactor and an atomic bomb is that
- (a) no chain reaction takes place in nuclear reactor while in the atomic bomb there is a chain reaction
- (b) the chain reaction in nuclear reactor is controlled
- (c) the chain reaction in nuclear reactor is not controlled
- (d) no chain reaction takes place in atomic bomb while it takes place in nuclear reactor
Answer(b) the chain reaction in nuclear reactor is controlled
Same physics — fission chain reactions. Both a reactor and an atomic bomb release nuclear energy by fission; the reactor controls the chain reaction, which is exactly the fission process this NDA item points to.
Of the following, which does not belong to a nuclear reactor ?
- (a) A turbine
- (b) A heat exchanger
- (c) A mechanism to reduce CO2 emission
- (d) A reaction chamber
Answer(c) A mechanism to reduce CO2 emission
Same topic — nuclear energy from fission. That 2024 (I) NDA item tests the parts of a nuclear reactor; this one names the process (fission) and the scientist behind its energy expression (Einstein).
- practice — not a real PYQ
The energy released in a nuclear reaction is explained by the equation
- (a)E = mc²
- (b)F = ma
- (c)E = hν
- (d)PV = nRT
Answer(a) E = mc² — Einstein's mass-energy equivalence.
- practice — not a real PYQ
The source of energy in the Sun is
- (a)Nuclear fission
- (b)Nuclear fusion
- (c)Chemical combustion
- (d)Radioactive decay only
Answer(b) Nuclear fusion — hydrogen nuclei fuse into helium in the Sun.