Assertion: Relative magnetic permeability has no units and no dimensions.

Reason: ${\mu }_{\mathrm{r}}=\frac{\mu }{{\mu }_0}$, where the symbols have their standard meaning.

Assertion: The net magnetic flux coming out of a closed surface is always zero.

Reason: Unlike poles of equal strength exist together.

Assertion: A magnet suspended freely in a uniform magnetic field experiences no net force, but a torque that tends to align the magnet along the field.

Reason: Net force $mB-mB=0$. But the forces on North and South poles being equal, unlike and parallel make up a couple that tends to align the magnet, along the field.

Assertion: If one arm of a U-tube containing a diamagnetic solution is placed in between the poles of a strong magnet with the level in line with the field, the level of the solution falls.

Reason: Diamagnetic substances are repelled by the magnetic field.

Assertion: Basic difference between an electric line and magnetic line of force is that former is discontinuous and the latter is continuous or endless.

Reason: No electric lines of forces exist inside a charged conductor but magnetic lines do exist inside a magnet.

Assertion: The earth's magnetic field is due to iron present in its core.

Reason: At a high-temperature magnet loses its magnetic property or magnetism.

Assertion: The ferromagnetic substances do not obey Curie's law.

Reason: At Curie point, ferromagnetic substances start behaving as a paramagnetic substance.