Nuclear Physics Archives

41. The hydrogen bomb and the uranium bomb are based, respectively on

The hydrogen bomb and the uranium bomb are based, respectively on

nuclear fusion and fission

fission and thermonuclear fusion

geothermal fission and fusion

geothermal fusion and fission

This question was previously asked in

UPSC CDS-1 – 2023

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The hydrogen bomb, also known as a thermonuclear bomb, is based on the principle of nuclear fusion. Nuclear fusion is a reaction in which two or more atomic nuclei collide at very high speeds and fuse to form a new, heavier nucleus, releasing a large amount of energy. This reaction typically requires extremely high temperatures, hence “thermonuclear”.
The uranium bomb, or atomic bomb (specifically a fission bomb), is based on the principle of nuclear fission. Nuclear fission is a nuclear reaction in which a heavy nucleus, such as an isotope of uranium or plutonium, splits into lighter nuclei, releasing a large amount of energy.

– Hydrogen bomb uses nuclear fusion.
– Uranium bomb uses nuclear fission.
– Both processes release enormous amounts of energy, but fusion generally releases more energy per unit mass than fission.

Fission bombs are used to ignite fusion reactions in hydrogen bombs, providing the necessary high temperatures and pressures. Nuclear power plants also use controlled nuclear fission reactions to generate electricity.

42. Which of the following statements about ‘fission’ is correct ? 1. It

Which of the following statements about ‘fission’ is correct ?

1. It is related with the creation of new individuals by means of cell division in unicellular organism.
2. It is related with the transformation of heavier nuclei into smaller nuclei.
3. It is related with the creation of a heavier nuclei by means of combining two higher nuclei.

Select the correct answer using the code given below :

1 only

2 only

1 and 2 only

1 and 3 only

This question was previously asked in

UPSC CDS-1 – 2021

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Statement 1 is correct as fission in biology refers to cell division for reproduction in unicellular organisms like bacteria and amoeba, resulting in the creation of new individuals. Statement 2 is correct as nuclear fission is a process in nuclear physics where a heavy atomic nucleus splits into smaller, lighter nuclei, often releasing energy. Statement 3 describes nuclear fusion, where lighter nuclei combine to form a heavier nucleus, which is the opposite of nuclear fission. Therefore, statements 1 and 2 correctly describe different types of ‘fission’.

Fission refers to splitting or division, occurring in both biological (cell division) and nuclear (heavy nucleus splitting) contexts. Fusion is the combining of nuclei.

Binary fission is the most common form of reproduction in prokaryotes. Nuclear fission is used in nuclear power plants and atomic bombs. Nuclear fusion occurs naturally in stars.

43. Scattering of α-particles by a thin gold foil suggests the presence o

Scattering of α-particles by a thin gold foil suggests the presence of

electron in an atom

proton in an atom

positively charged nucleus at the centre of an atom

isotopes of gold

This question was previously asked in

UPSC CDS-1 – 2020

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Rutherford’s alpha-particle scattering experiment demonstrated that a small, dense, positively charged nucleus exists at the center of an atom.

The deflection of positively charged alpha particles at large angles, and the reflection of a few back towards the source, indicated that they were encountering a strong positive charge concentrated in a very small volume within the atom, which was termed the nucleus.

The vast majority of alpha particles passed straight through the gold foil, leading to the conclusion that most of the atom’s volume is empty space. This experiment disproved the plum pudding model of the atom.

44. Who proposed the ‘Plum Pudding Model’ for an atom?

Who proposed the ‘Plum Pudding Model’ for an atom?

Antoine Lavoisier

Robert Boyle

Ernest Rutherford

J.J. Thomson

This question was previously asked in

UPSC CDS-1 – 2017

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J.J. Thomson proposed the ‘Plum Pudding Model’ for an atom.

The Plum Pudding Model suggested that the atom was a sphere of positive charge with negatively charged electrons embedded within it, much like plums in a pudding.

Ernest Rutherford’s gold foil experiment later disproved the Plum Pudding Model, leading to the development of the nuclear model of the atom. Antoine Lavoisier is known as the ‘father of modern chemistry’ for his work on the law of conservation of mass. Robert Boyle is known for Boyle’s Law relating to gases.