Gauss law in magnetism signifies that

The correct answer is Option (2) → Net flux through closed surface is zero, monopole does not exist

Gauss's law for magnetism states that the net magnetic flux through any closed surface is zero.

    \( \displaystyle \oint \vec{B}\cdot d\vec{S} = 0 \)

Every magnetic field line that enters a closed surface also leaves it, because magnetic field lines form closed loops. There is no isolated north or south pole (magnetic monopole) inside to act as a source or sink of the lines.

Option (1) Magnetic lines of force can pass through a closed surface — Incorrect. Lines can pass through a closed surface, but this does not express the law; the law is about the net flux being zero.

Option (2) Net flux through closed surface is zero, monopole does not exist — Correct. Zero net flux through every closed surface means that magnetic monopoles do not exist.

Option (3) Net flux is always μ₀ times the net charge enclosed — Incorrect. This mixes the law with Gauss's law of electrostatics; the magnetic flux through a closed surface is zero, not proportional to an enclosed charge.

Option (4) There always exist a monopole — Incorrect. Monopoles would make the net flux non-zero; the law says they do not exist.

NCERT (2026-27):
Magnetism and Gauss’s Law – “… The difference between the Gauss’s law of magnetism and that for electrostatics is a reflection of the fact that isolated magnetic poles (also called monopoles) are not known to exist. There are no sources or sinks of B; the simplest magnetic element is a dipole or a current loop. All magnetic phenomena can be explained in terms of an arrangement of dipoles and/or current loops. Thus, Gauss’s law for magnetism is:

    The net magnetic flux through any closed surface is zero.”