NEET Practice Questions (MCQs) with Answers & Solutions

The electromagnetic force (C) is stronger than the weak nuclear force (A) and the gravitational force (B). The correct order of the forces by their strength is $ C extgreater A extgreater B $. This is a well-established fact in physics where gravitational force is the weakest, followed by the weak nuclear force, and then the electromagnetic force.

The strong nuclear force does not act on electrons. This force acts primarily between protons and neutrons within the atomic nucleus, binding them together. Electrons, which reside outside the nucleus, are not influenced by the strong nuclear force.

$ F_1 = { kq_1 q_2 \over r_1^2 } $ $ F_2 = { kq_1 ' q_2' \over r_2 ^2 } $

If the resultant external force acting on a system is zero, the linear momentum of the system remains constant due to the conservation of linear momentum. Similarly, if the resultant external torque acting on a system is zero, the angular momentum of the system remains constant due to the conservation of angular momentum.

The homogeneity and isotropy of space imply that physical laws do not change from one point to another (homogeneity) and are the same in every direction (isotropy). This results in the conservation of linear momentum (due to homogeneity) and angular momentum (due to isotropy).

The gravitational force between two bodies follows an inverse-square law, which means it is inversely proportional to the square of the distance between them. Mathematically, it is represented as $F \\propto r^{-2}$.

The correct matching is as follows:
(1) Space is isotropic - (S) Conservation of angular momentum.
(2) Space is homogeneous - (P) Conservation of linear momentum.
(3) Time is homogeneous - (Q) Conservation of energy.
(4) Time is isotropic - (R) Conservation of charge still not known.

Becquerel is a unit of radioactivity and not a unit of length. Other options such as light year, fermi, and $A^\circ$ (angstrom) are units of length.