Magnetism is lost when an external source of the magnetic field is removed. This type of magnet is known as _______.

A magnetic field:

$1$. Never exerts a force on a charged particle.

$2$. Always exerts a force on a charged particle.

$3$. Exerts a force on a charged particle if it is moving across the magnetic lines of force.

$4$. Exerts a force on a charged particle if it is moving along the magnetic lines of force.

Which of the statements given above is/are correct?

Consider the following statements:

Statement I

In the process ${}_1{}^{3}T\to {}_2{}^{3}He+X$, $X$ is electron.

Statement II

In the transformation sequence ${}_Z{}^{A}X\to {}_{Z-2}{}^{A-4}Y\to {}_{Z-2}{}^{A-4}Z\to {}_{Z-1}{}^{A-4}K$.

The decays in the order $\alpha , \gamma , \beta$.

Consider the following statements:

1. Electromagnetic waves cannot propagate without a medium.

2. Radio waves have the maximum wavelength.

3. All components of the electromagnetic spectrum in a vacuum, have the same energy.

Which of the statements given above are incorrect?

Out of the following which is the non-magnetic substance?

(A) Iron

(B) Nickel

(C) Cobalt

(D) Copper