Which
electromagnetic
waves have the
largest wavelength?

The electromagnetic waves with the longest wavelengths are the ones we call "radio waves".

They're anything with a wavelength of 1 millimeter or more. (Frequency of 300 GHz or less.)

That's longer than gamma rays, X-rays, ultraviolet, visible light, and infrared radiation.

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.

this is a good question! i'll do some research and come back when i have the answer!