Sunspots are cooler than the surrounding solar surface because

Because the convection process stops and hotter plasma doesn't replace the cooler plasma on the surface

Explanation:

Sun spots are the darker and relatively cooler regions on the surface of the Sun (photosphere). Their temperature is around 1000° C lower than the Sun's surface.

Reason: The Sun's surface is granulated because of the convection process happening in the layer just below the photosphere. Because of the convection, hotter plasma comes on the surface, release energy, and then gets replaced by the hotter plasma. Just like tea or water boils. The places where magnetic field line enter into and exit from the surface, this convection process stops. Thus these area starts getting cooler and appear black in color.

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.

see earlier answer