Astronomers suspect that a galaxy's type can be affected both by the conditions in the protogalactic cloud from which it forms ("initial conditions") and by later interactions with other galaxies. each item below describes either a condition n a protogalactic cloud or a later interaction. match these items to the galaxy type you would expect to form as a result.
1. stars form rapidly as the protogalactic could shrinks
2. most protogalactic gas settles into a disk
3. protogalactic cloud has high density
4. a galaxy collision strips away gas
5. protogalactic cloud rotates very slowly
6. protogalactic cloud has high angular momentum
a. elliptical galaxy
b. spiral galaxy

answer: the answer is a

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.