Kiera is preforming an experiment. she completed her first experimental trial and recorder the results. when she repeated the trial, she got a completely different result. what should kiera do?

She should go through her experimental equipment, setup, and procedure with a fine-tooth comb, to find any little thing that she didn't consider during the first two runs.

Then, she should run the experiment again, one time, two times, or a hundred times more, until she's getting consistent, repeatable results.

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.