Asystem consisting of a negatively-charged particle and an electric field : a. loses electric potential energy when the charged particle moves in the direction of the field. b. gains potential difference and electric potential energy when the charged particle moves in the direction of the field. c. gains kinetic energy when the charged particle moves in the direction of the field. d. gains potential difference and kinetic energy when the charged particle moves in the direction of the field. e. gains electric potential energy when the charged particle moves in the direction of the field.

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.

c because the news are a source of information of things that happen on the daily and shows evidence about that particular topic