Which of the following is true concerning gamma radiation?
a. the mass number of the radioisotope decreases by four.
b. the atomic number of the radioisotope decreases by two.
d. neither the mass number nor the atomic number changes.

 D. Neither the mass number nor the atomic number changes.

Explanation:

1.) Alpha decay: In this process, alpha particles is emitted when a heavier nuclei decays into lighter nuclei. The alpha particle released has a charge of +2 units.  The mass number of the radioisotope decreases by four and the The atomic number of the radioisotope decreases by two.

2.)Beta-decay: In this process, a neutron gets converted into a proton and an electron releasing a beta-particle. The beta particle released carries a charge of -1 units.  The mass number remains same but the atomic number decreases by

3.) Gamma ray emission: in this process, an unstable nuclei gives off excess energy by a spontaneous electromagnetic process and releases . These radiations does not carry any charge and are electrically neutral.

Neither the mass number nor the atomic number changes.