Which of the following best describes a direct current?

A. A circuit that has only series or only parallel components

B. Charge that jiggles back and forth very quickly

C. Charge that moves in a single direction

D. A circuit that has both series and parallel components

charge that moves in a single direction

hope this helped :)

C. Charge that moves in a single direction

Explanation:

A P E X

the average speed is 24.57 km/hr

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.