Atomic Structure

Total Questions: 39

1. Who is regarded as the Father of Modern Chemistry? [65th B.P.S.C. (Pre) 2019]

(a) Rutherford
(b) Einstein
(c) Lavoisier
(d) C.V. Raman
(e) None of the above/More than one of the above

Correct Answer: (c) Lavoisier

Solution:

French nobleman and chemist Antoine Lavoisier is regarded as the 'Father of Modern Chemistry'. Lavoisier is most noted for his discovery of the role oxygen plays in combustion. He recognized and named oxygen (1778) and hydrogen (1783), wrote the first extensive list of elements and helped to reform chemical nomenclature.

2. The positively charged part at the centre of an atom is called as: [63rd B.P.S.C. (Pre) 2017]

(a) Proton
(b) Neutron
(c) Electron
(d) Nucleus
(e) None of the above/More than one of the above

Correct Answer: (d) Nucleus

Solution:The positively charged part at the centre of an atom is called as nucleus. The atomic nucleus is the small, dense region consisting of proton and neutron at the centre of an atom.

3. Constituents of atomic nucleus are – [U.P. P.C.S. (Pre) 1996, 41st B.P.S.C. (Pre) 1996, 43rd B.P.S.C. (Pre) 1999]

(a) Electron and proton
(b) Electron and neutron
(c) Proton and neutron
(d) Proton, neutron and electron

Correct Answer: (c) Proton and neutron

Solution:

The constituents of an atom are protons, neutrons and electrons. The protons and neutrons (nucleons) are found in the nucleus of atoms. The nucleus of an atom is surrounded by electrons.

4. The nucleus of an atom consists of: [67th B.P.S.C. (Pre) (Re. Exam) 2022]

(a) electrons and neutrons
(b) electrons and protons
(c) protons and neutrons
(d) electrons only
(e) None of the above/More than one of the above

Correct Answer: (c) protons and neutrons

Solution:The constituents of an atom are protons, neutrons and electrons. The protons and neutrons (nucleons) are found in the nucleus of atoms. The nucleus of an atom is surrounded by electrons.

5. Which among the following is an incorrect option? [67th B.P.S.C. (Pre) 2022]

(a) Atom is electrically neutral due to the presence of protons and electrons inside the nucleus.
(b) Electrons are negatively charged and have negligible mass.
(c) Atomic number is the number of protons in an atom of an element.
(d) Isotopes are useful as nuclear fuel, in medical field; in carbon dating, etc.
(e) None of the above/More than one of the above

Correct Answer: (a) Atom is electrically neutral due to the presence of protons and electrons inside the nucleus.

Solution:An atom consists of a positively charged nucleus, surrounded by one or more negatively charged particles called electrons. The atomic nucleus consists of protons and neutrons while electrons revolve around the nucleus. The positive charges in an atom equal the negative charges, so the atom has no overall charge; it is electrically neutral. Statements of options (b), (c), and (d) are correct.

6. Which of the following statement about molecular structure is correct: [R.A.S/R.T.S. (Pre) 1992]

(a) Neutron and electron are found inside the nucleus and protons revolve around the nucleus.
(b) Electron and proton are inside the nucleus and neutron revolve around the nucleus.
(c) Proton and neutron are inside the nucleus and electrons revolve around the nucleus.
(d) Proton, neutron and electron all are inside the nucleus.

Correct Answer: (c) Proton and neutron are inside the nucleus and electrons revolve around the nucleus.

Solution:

The correct statement about molecular structure is Proton and neutron are inside the nucleus and electrons revolve around the nucleus.

The nucleus is the dense central region of an atom.

Protons and neutrons are the particles found inside the nucleus. Protons carry a positive charge, while neutrons are neutral (have no charge).

Electrons are negatively charged particles that orbit the nucleus in specific energy levels or shells.

7. Which of the following is not a part of an atom? [M.P.P.C.S. (Pre) 2005]

(a) Electron
(d) Photon
(b) Proton
(d) Neutron

Correct Answer: (d) Photon

Solution:Proton, electron and neutron are part of an atom, but the photon is associated with light energy and also known as the energy packet of light.

8. A single type of atom is found in – [53rd to 55th B.P.S.C. (Pre) 2011]

(a) Compounds of minerals
(b) Mixture of minerals
(c) Native elements
(d) None of the above

Correct Answer: (c) Native elements

Solution:

Native elements are substances that occur naturally in elemental form, meaning they are composed of only one type of atom. Examples include gold (Au), silver (Ag), copper (Cu), sulfur (S), and diamond (which is made of only carbon atoms).

Compounds of minerals are formed when two or more different types of atoms are chemically bonded together in a fixed ratio.

Mixture of minerals involves the physical combination of different minerals, each of which can be a compound or a native element, thus containing one or more types of atoms.

9. The atomic nucleus was discovered by: [R.A.S/R.T.S. (Pre) 2003]

(a) Rutherford
(b) Dalton
(c) Einstein
(d) Thompson

Correct Answer: (a) Rutherford

Solution:The nucleus is a very dense region consisting of protons and neutrons at the centre of an atom. It was discovered in 1911 as a result of Ernest Rutherford’s interpretation of the 1909 Geiger–Marsden gold foil experiment. The proton-neutron model of the nucleus was proposed by Dmitri Ivanenko in 1932.

10. Consider the following events, and arrange them in correct chronological order starting from the earliest to the last activity: [U.P. R.O/A.R.O. (Pre) 2023]

(I) Discovery of pi meson
(II) Discovery of neutron
(III) Discovery of electron
(IV) Discovery of proton

Select the correct answer from the code given below:
Code:

(a) (III), (II), (IV), (I)
(b) (III), (IV), (II), (I)
(c) (I), (III), (IV), (II)
(d) (III), (IV), (I), (II)
(e) (IV), (III), (II), (I)

Correct Answer: (b) (III), (IV), (II), (I)

Solution:

(III) Discovery of electron: The electron was the first subatomic particle to be discovered. J.J. Thomson is credited with its discovery in 1897 through his experiments with cathode rays.

(IV) Discovery of proton: Ernest Rutherford is credited with the discovery of the proton around 1911-1919. His gold foil experiment provided evidence for a positively charged nucleus containing protons.

(II) Discovery of neutron: James Chadwick discovered the neutron in 1932. The existence of a neutral particle within the nucleus was needed to explain the mass discrepancy between the atomic number and the atomic weight.

(I) Discovery of pi meson: Hideki Yukawa predicted the existence of mesons in 1935 as particles that mediate the strong nuclear force. The pi meson (pion) was experimentally discovered in 1947 by Cecil Powell, César Lattes, and Giuseppe Occhialini.

Therefore, the correct chronological order is III, IV, II, I.

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Atomic Structure

1. Who is regarded as the Father of Modern Chemistry? [65th B.P.S.C. (Pre) 2019]

2. The positively charged part at the centre of an atom is called as: [63rd B.P.S.C. (Pre) 2017]

3. Constituents of atomic nucleus are – [U.P. P.C.S. (Pre) 1996, 41st B.P.S.C. (Pre) 1996, 43rd B.P.S.C. (Pre) 1999]

4. The nucleus of an atom consists of: [67th B.P.S.C. (Pre) (Re. Exam) 2022]

5. Which among the following is an incorrect option? [67th B.P.S.C. (Pre) 2022]

6. Which of the following statement about molecular structure is correct: [R.A.S/R.T.S. (Pre) 1992]

7. Which of the following is not a part of an atom? [M.P.P.C.S. (Pre) 2005]

8. A single type of atom is found in – [53rd to 55th B.P.S.C. (Pre) 2011]

9. The atomic nucleus was discovered by: [R.A.S/R.T.S. (Pre) 2003]

10. Consider the following events, and arrange them in correct chronological order starting from the earliest to the last activity: [U.P. R.O/A.R.O. (Pre) 2023]

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