Question

As per Thompson's model, all atoms are neutral. What about the alpha particles? Are they neutral too? ​

Answer 1

Alpha particles aren't neutral .They are +2 charges. Actually, they are just the nucleus of helium atoms.

Answer 2

Alpha particle → 2 Protons+2 Neutrons 

We know that alpha are made of 2 protons and 2 neutrons. By this it self we can say that Alpha particles aren't neutral.