Question

Assertion: The microscopic domain of physics deals with the constitution and structure of matter at the minute scales of atoms and nuclei.
Reason: Classical physics is adequate to deal with the microscopic domain of physics.

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true and reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer 1

Hint: In classical physics we study motion of particles or bodies by knowing their positions, forces, velocities, momentum and energies. In the microscopic domain, we deal with particles such as electrons, protons and neutrons.

Complete answer:
Classical physics has mainly been divided into two domains: kinematics and dynamics. In kinematics we talk about the motion of a body by knowing its position and velocities generally, whereas dynamics deals with knowing the forces acting on the body and details of the motion. As we go to the atomic realm, we deal with particles that have much smaller sizes. These particles are so tiny that we cannot observe them but we can only detect their presence. Various theories have been devised in order to determine the nature of the atom (which is the fundamental unit of an element) and its constituents. A very fundamental principle of uncertainty is present very deeply at such scales. The position and momentum of a particle like an electron cannot be determined with precision. Therefore these particles are fundamentally different from the macroscopic particles like the ones we deal with in classical physics. The laws of classical physics cannot be applied to subatomic particles because with classical mechanics we are allowed to precisely determine position and momentum for a particle simultaneously.
Therefore, the assertion that the microscopic domain of physics deals with the constitution and structure of matter is a correct statement but the reason is an incorrect statement.

So, the correct answer is “Option C”.

Note:
 The principle of uncertainty can be a little tricky to understand and also quite absurd. Therefore, for this answer, one only needs to keep in mind that quantum mechanics is for subatomic particles and classical mechanics is for macroscopic particles like the ones which we can see with our naked eyes.