Television sets. what does it mean to refer to a 20-in tv set or a 25-in tv set? such units refer to the diagonal of the screen. a 35-in tv set also has a width of 28 inches. what is its height?

21 inch

Explanation:

It means that the length of the diagonal of the TV is 20 inch or 25 inch.

Width of TV = 28 inch

diagonal of TV = 35 inch

Let L be the length of the TV

Use Pythagorean theorem

Diagonal^2 = length^2 + width^2

35^2 = L^2 + 28^2

L^2 = 1225 - 784

L^2 = 441

L = 21 inch

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.