The e/m is constant for : (More than one option could be correct)Select one or more(A) Cathode rays12(B) Positive rays2(C) Neutron8(D) Proton9

To determine which options have a constant e/m value, we need to consider the properties of each option.

(A) Cathode rays: Cathode rays are streams of electrons that are produced in a cathode ray tube. The e/m value for electrons in cathode rays is constant.

(B) Positive rays: Positive rays are streams of positively charged particles, typically ions. The e/m value for positive ions in positive rays is also constant.

(C) Neutron: Neutrons are electrically neutral particles, meaning they have no charge. Since they have no charge, the e/m value for neutrons is not applicable.

(D) Proton: Protons are positively charged particles found in the nucleus of an atom. The e/m value for protons is also constant.

Based on this information, the options with a constant e/m value are (A) Cathode rays and (D) Proton.