A nuclear radiation when passes through a magnetic field which is perpendicularly into the paper as shown below, deflects towards B. Identify the nuclear radiation

Hint: In order to solve this question we need to understand nuclear radiation and motion of a particle in a magnetic field. Every atom is made up of mainly two parts, one is the nucleus and other is electrons spinning around it. So for particles having large atomic numbers (atomic number is defined as number of protons or electrons) nucleus is quite unstable due to large Coulomb repulsion between protons due to their large number so the emit radiation is known as alpha, beta and gamma radiation. This is known as nuclear radiation.

Complete step-by-step solution:
As stated there are three types of nuclear radiation, alpha beta and gamma radiation
Where alpha radiation is termed as highly energetic and fast moving helium nucleus and it is positively charged having less penetrating power then gamma and beta radiation
Beta radiation is a high speed electron or positron emitted by a radioactive decay of an atomic nucleus. There are two forms of beta decay one is ${\beta ^ + }$ and other is ${\beta ^ - }$
Gamma radiation is termed as neutral radiation as it has no charges but it has the highest penetrating power.
So when a particles enters in magnetic field then it suffers deflection due to magnetic force on it given by, $\vec F = q(\vec v \times \vec B)$
If particle enters perpendicularly in a magnetic field then the force magnitude is given by, $F = qvB$
And it is always directed towards a point so particle moves in a circular path
Gamma radiation does not have a charge so it goes undeflected while alpha radiation has a positive charge so it moves in an anticlockwise manner while Beta electrons have negative charge so it moves in a clockwise manner.
This is true only when the magnetic field is inside the plane of paper.
So according to the figure since the ray deflected toward B in clockwise manner so it is beta radiation or more precisely it is ${\beta ^ - }$ radiation.

Note: It should be remembered that deflection depends on velocity and charge of particle entering however it must be noted that only when the particle velocity is perpendicular to magnetic field then it traces circular path but if it is parallel to magnetic field then it goes undeflected as there would be no force on it.