Physics

Nuclear and Atomic Physics

571 Questions

Nuclear and atomic physics explores the components and properties of the nucleus, including isotopes, radioactive decay, and fundamental forces. These concepts are essential for various competitive exams requiring a strong foundation in physics. The provided questions cover structural properties, mass, energy equivalence, and particle interactions.

Nucleus propertiesIsotopes and mass numberAlpha particle scatteringNuclear forcesMass energy equivalenceBeta particle emission

Nuclear and Atomic Physics Questions

Multiple choice

Tritium nucleus consists of

  1. one proton and two neutrons

  2. two neutrons and two protons

  3. two protons and one neutron

  4. one neutron and one proton
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Tritium (hydrogen-3 or ³H) is a radioactive isotope of hydrogen consisting of one proton and two neutrons in its nucleus. It is the heaviest naturally occurring hydrogen isotope, with deuterium (²H) having one proton and one neutron, and protium (¹H) having just one proton.

Multiple choice

Every element on the periodic chart is radioactive, though the more stable elements have half-lives which are thousands and thousands of years long. When an atom decays, it splits into two or more smaller atoms. Even considering the fusion taking place inside of stars, there is only a negligible tendency for smaller atoms to transmute into larger ones. Thus, the ratio of lighter to heavier atoms in the universe is increasing at a measurable rate. Which of the following sentences provides the most critical continuation of this paragraph?

  1. Without radioactive decay of atoms, there could be no solar combustion and no life as we know it.

  2. Therefore, it is imperative that scientists begin developing ways to reverse the trend and restore the proper balance between the lighter and the heavier elements.

  3. Consequently, it is possible to use a shifting ratio of light to heavy atoms to calculate the age of the universe.

  4. Therefore, there are now more light elements in the universe than heavy ones.

  5. As a result, the fusion taking place inside stars has to produce enough atoms of the heavy elements to offset the radioactive decay of large atoms elsewhere in the universe.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

(3) The last sentence of the paragraph is very important. It tells us that the proportion of light atoms in the universe is increasing (because heavy ones decay into light ones, but the reverse process does not occur) and that this trend can be measured. By extrapolation back into time on the basis of present trends, scientists can find out when it all began.

Multiple choice

Which among the following doesn't undergo any division?

  1. Proton

  2. Neutron

  3. Atom

  4. Molecules

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Atoms are the smallest units of elements that retain the element's chemical properties and do not undergo division by chemical means. Protons and neutrons are subatomic particles within the atom's nucleus, while molecules are formed when atoms chemically bond together. While atoms can undergo nuclear fission (splitting of the nucleus), this is a nuclear process, not chemical division. The atom as a complete unit cannot be divided through ordinary chemical processes.

Multiple choice

Chadwick discovered

  1. neutron

  2. proton

  3. electron

  4. mesons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Neutrons were first discovered in 1932 by James Chadwick.

Multiple choice

Directions: This question presents a sentence, all or part of which is underlined. Beneath the sentence you will find five ways of phrasing the underlined part. The first of these repeats the original; the other four are different. If you think the original is best, choose the first answer; otherwise choose one of the others.

Very occasionally a neutrino will collide with a neutron in a chloride nucleus, turning the latter into a proton and simultaneously turning the chlorine atom to radioactive argon.

  1. turning the latter into a proton and simultaneously turning the chlorine atom to radioactive argon

  2. turning the latter to a proton and simultaneously turning the chlorine atom to radioactive argon

  3. turning the later into a proton and simultaneously turning the chlorine atom to radioactive argon

  4. turning the latter into a proton and simultaneously turning the chlorine atom into radioactive argon

  5. turning the later into a proton and simultaneously turning the chlorine atom into a radioactive argon
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Explanation for (1): 'Turning' is followed by 'into'.

Explanation for (2): Turning' is followed by 'into'. This option compounds the error of preposition.

Explanation for (3): Turning' is followed by 'into'. This option compounds the error of preposition by adding the error of adjective ('later' in place of 'latter').
Justification for (4): 'Turning' is followed by 'into'.  The error stands corrected in option (4). Explanation for (5): Turning' is followed by 'into'. This option corrects the error of preposition but adds the error of adjective ('later' in place of 'latter').

Multiple choice

Rutherford inferred which of the following when he observed that 1 in 100000 alpha-particles completely rebound on hitting the foil?

  1. Nucleus in atom is very small as compared to the total size.

  2. Nucleus is the centre of mass for an atom.

  3. Nucleus is positively charged.

  4. Positive charge of the atom occupies very little space.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rutherford inferred that nucleus in atom is very small as compared to the total size on observing that 1 in 100000 alpha-particles completely rebound on hitting the foil.

Multiple choice

Which of the following observations of Rutherford gold foil experiment leads to the inference that there is a large empty space in atom?

  1. 1 in 1000000 particles completely rebound on hitting the foil.

  2. Very few particles were deflected.

  3. Most of the alpha particles passed through the gold foil without getting deflected.

  4. Some particles suffered a small deflection.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 Most of the alpha particles passed through the gold foil without getting deflected.

Multiple choice

Which of the following was the main limitation of Rutherford's model of atom?

  1. Atom is positively charged.

  2. Atoms of the same element are similar in all aspects.

  3. Arrangement of electrons and protons was not clear.

  4. Nucleus and electrons are held together by electrostatic force.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This was a limitation of Rutherford's model. He said that nucleus and electrons are held together by electrostatic force while revolving around nucleus, but this lead to confusion. According to the electromagnetic theory, an accelerating charged particle must emit radiation and lose energy. Because of this loss of energy, the electron would slow down and will not be able to withstand the attraction of the nucleus. As a result, the electron should follow a spiral path and ultimately, fall into nucleus. But, it does not happen.

Multiple choice

Electrons revolve round the nucleus because of

  1. cohesive force

  2. adhesive force

  3. centripetal force

  4. centrifugal force
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Rutherford assumed that electrons are revolving around the nucleus in circular orbits of all possible redii. The necessary centripetal forces for circular motion of electrons around the nucleus is provided by electrostatic force of attraction between electrons and nucleus. So 3rd option is the correct answer.