Which of the following represents an alpha particle?

The correct answer is option 2. \(_2^4He\).

An alpha particle is a type of particle that consists of two protons and two neutrons bound together. It is essentially a helium-4 nucleus. Let's break down the representation \( ^{4}_{2}He \):

The superscript (4) is the mass number, representing the total number of protons and neutrons in the nucleus. In this case, there are 2 protons and 2 neutrons, giving a total of 4.

The subscript (2) is the atomic number, indicating the number of protons in the nucleus. For helium, the atomic number is 2, as helium has 2 protons.

So, \( ^{4}_{2}He \) represents an alpha particle, which is a helium nucleus composed of 2 protons and 2 neutrons.