light ray 1 strikes the smooth surface of a mirror as shown below.

ray one hits the mirror, and ray 2 is going away from the mirror just to the right of ray 1, ray 3 is bouncing off just to the right of ray 2, ray 4 is bouncing off next to ray 3, and ray 5 is bouncing off the the right of ray 4.

which of the following is the reflected ray for ray 1?
ray 2
ray 3
ray 4
ray 5

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.

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