Radioactive substances decay and emit alpha, beta, positron, and gamma particles in the process of converting to stable nuclei. An alpha particle has two protons and two neutrons, is relatively heavy and deflected by electrical and magnetic fields. Beta particles are fast moving electrons which are greatly deflected by electrical and magnetic fields. Gamma particles (highly energetic) are neutral and not deflected electrical and magnetic fields. Positron is positively charged beta particle. Opposite charges attract each other. So we can say that alpha particle and positron being positively charged are attracted towards the negative plate. Alpha particle is heavy, so it is slightly deflected towards the negative plate. Beta particle being negatively charged is deflected towards the positive plate and gamma particle is neutral and not deflected in the electrical field.
Therefore, the correct answer is,
A. Beta particle
B. Gamma particle
C. Alpha particle
D. Positron
