Grade 12 Exam  >  Grade 12 Tests  >  Assertion & Reason Test: Atoms - Grade 12 MCQ

Assertion & Reason Test: Atoms - Grade 12 MCQ


Test Description

11 Questions MCQ Test - Assertion & Reason Test: Atoms

Assertion & Reason Test: Atoms for Grade 12 2024 is part of Grade 12 preparation. The Assertion & Reason Test: Atoms questions and answers have been prepared according to the Grade 12 exam syllabus.The Assertion & Reason Test: Atoms MCQs are made for Grade 12 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Assertion & Reason Test: Atoms below.
Solutions of Assertion & Reason Test: Atoms questions in English are available as part of our course for Grade 12 & Assertion & Reason Test: Atoms solutions in Hindi for Grade 12 course. Download more important topics, notes, lectures and mock test series for Grade 12 Exam by signing up for free. Attempt Assertion & Reason Test: Atoms | 11 questions in 22 minutes | Mock test for Grade 12 preparation | Free important questions MCQ to study for Grade 12 Exam | Download free PDF with solutions
Assertion & Reason Test: Atoms - Question 1

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): According to Rutherford, the atomic model, the path of electrons is parabolic.

Reason (R): Rutherford could not explain the stability of atoms.

Detailed Solution for Assertion & Reason Test: Atoms - Question 1
According to Rutherford, “the entire positive charge and most of the mass of the atom is concentrated in a small volume called the nucleus, with electrons revolving around the nucleus just as planets revolve around the Sun.” So the assertion is false.

The electron orbiting around the nucleus radiates energy. As a result, the radius of the orbit continuously decreases and the electrons fall into the nucleus. So, the stability of atoms is not explained. Hence the reason is true.

Assertion & Reason Test: Atoms - Question 2

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Bohr model is not applicable for multi-electron models.

Reason (R): Bohr model cannot account for sublevel (s, p, d, f) orbitals and electron spin.

Detailed Solution for Assertion & Reason Test: Atoms - Question 2
Bohr model works well for H and He+ having one electron only. But it does not work for multi-electron atoms, since it cannot account for sublevel (s, p, d, f) orbitals and electron spin. So, assertion and reason both are true and reason explains the assertion.
1 Crore+ students have signed up on EduRev. Have you? Download the App
Assertion & Reason Test: Atoms - Question 3

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Bohr postulated that the electrons in stationary orbits around the nucleus do not radiate.

Reason (R): According to classical Physics, all moving electrons radiate.

Detailed Solution for Assertion & Reason Test: Atoms - Question 3
Bohr postulated that electrons in stationary orbits around the nucleus do not radiate. This is true.

According to classical Physics, the moving electrons radiate only when they jump from a higher energy orbit to the lower energy orbit. So, the reason is false.

Assertion & Reason Test: Atoms - Question 4

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): In the α-particle scattering experiment, most of the α-particles pass undeviated.

Reason (R): Most of the space in the atom is empty.

Detailed Solution for Assertion & Reason Test: Atoms - Question 4
Most of the α-particles pass roughly in a straight line (within 10) without deviation. This shows that no force is acting on them. So the assertion is true.

Most of the space in the atom is empty. Only 0.14% of α-particles are scattered more than 1°.

Assertion & Reason Test: Atoms - Question 5

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : According to classical theory the proposed path of an electron in Rutherford atom model will be parabolic.

Reason : According to electromagnetic theory an accelerated particle continuously emits radiation.

Detailed Solution for Assertion & Reason Test: Atoms - Question 5

Explanation: The Assertion is incorrect because, according to classical theory, the proposed path of an electron in the Rutherford atom model would not be parabolic; it would be elliptical or circular. The model predicted that electrons orbit the nucleus much like planets orbiting the sun, which would lead to closed orbits, not open parabolic paths.

The Reason is correct in stating that according to classical electromagnetic theory, an accelerated charged particle emits radiation. However, this emission of radiation would cause the electron to lose energy and spiral into the nucleus rather than follow a parabolic path. This was one of the key issues with the Rutherford model, as it could not explain the stability of atoms, since classical mechanics would predict that electrons should crash into the nucleus rather than staying in a stable orbit.

Assertion & Reason Test: Atoms - Question 6

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Electrons in the atom are held due to Coulomb forces.

Reason : The atom is stable only because the centripetal force due to Coulomb’s law is balanced by the centrifugal force.

Detailed Solution for Assertion & Reason Test: Atoms - Question 6

Correct option is C. If the Assertion is correct but Reason is incorrect.

Explanation: The Assertion is correct. Electrons in an atom are indeed held in their positions due to the Coulomb force, which is the electric force between the positively charged nucleus and the negatively charged electrons.

However, the Reason is incorrect. The stability of an atom is not due to a balance of centripetal and centrifugal forces. The classical concept of centrifugal force balancing the Coulombic centripetal force, as would be the case in a planetary model of the atom, is not valid in quantum mechanics. In quantum mechanics, electrons occupy orbitals around the nucleus without necessarily revolving in the classical sense, and their positions and energies are described by wave functions. The stability of the atom is due to the quantum mechanical principles, including the Heisenberg Uncertainty Principle and the Pauli Exclusion Principle, not a balance of classical forces.

Assertion & Reason Test: Atoms - Question 7

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Between any two given energy levels, the number of absorption transitions is always less than the number of emission transitions.

Reason : Absorption transitions start from the lowest energy level only and may end at any higher energy level. But emission transitions may start from any higher energy level and end at any energy level below it.

Assertion & Reason Test: Atoms - Question 8

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : The force of repulsion between atomic nucleus and α-particle varies with distance according to inverse square law.

Reason : Rutherford did α-particle scattering experiment.

Detailed Solution for Assertion & Reason Test: Atoms - Question 8
Rutherford confirmed that the repulsive force of α- particles due to the nucleus varies with distance according to inverse square law and that the positive charges are concentrated at the centre and not distributed throughout the atom.
Assertion & Reason Test: Atoms - Question 9

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate.

Reason: According to classical physics all moving electrons radiate.

Detailed Solution for Assertion & Reason Test: Atoms - Question 9
Bohr postulated that electrons in stationary orbits around the nucleus do not radiate. This is the one of Bohr’s postulates, According to this the moving electrons radiate only when they go from one orbit to the next lower orbit.
Assertion & Reason Test: Atoms - Question 10

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Hydrogen atom consists of only one electron but its emission spectrum has many lines.

Reason : Only the Lyman series is found in the absorption spectrum of hydrogen atoms whereas in the emission spectrum, all the series are found.

Detailed Solution for Assertion & Reason Test: Atoms - Question 10
When the atom gets appropriate energy from outside, then this electron rises to some higher energy level. Now it can return either directly to the lower energy level or come to the lowest energy level after passing through other lower energy levels hence all possible transitions take place in the source and many lines are seen in the spectrum.
Assertion & Reason Test: Atoms - Question 11

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : In Lyman series, the ratio of minimum and maximum wavelength is 3/4

Reason : Lyman series constitute spectral lines corresponding to transition from higher energy to ground state of the hydrogen atom.

Detailed Solution for Assertion & Reason Test: Atoms - Question 11

For the Lyman series, n1 ​= 1. For the next level, n2 ​= 2

so by eq.1 the ratio of minimum and maximum wavelength is 3/4.

Hence the assertion is correct.

Yes, the Lyman series constitutes spectral lines corresponding to the transition from higher energy to the ground state of the hydrogen atom. so the reason is also correct. But the reason is not the correct explanation of the assertion. Hence option 'B' is correct.

Information about Assertion & Reason Test: Atoms Page
In this test you can find the Exam questions for Assertion & Reason Test: Atoms solved & explained in the simplest way possible. Besides giving Questions and answers for Assertion & Reason Test: Atoms, EduRev gives you an ample number of Online tests for practice

Top Courses for Grade 12

Download as PDF

Top Courses for Grade 12