14 uranium atoms in pure uranium
<u>Answer: </u>The correct answer is Option D.
<u>Explanation:</u>
Unstable isotopes are defined as the isotopes which have excess of neutrons as compared to the stable form of the nucleus of an atom.
These isotopes attain stability by undergoing a spontaneous nuclear decay. The isotopes which are unstable have another name and are known as radioactive isotopes or radioisotopes.
These isotopes undergoes decay by 4 processes: Alpha decay, beta decay, gamma emission and positron decay.
Hence, the correct answer is option D.
<span>Mass Number = (Atomic Number) + (Number of Neutrons) so you solve for the Number of Neutrons and you get:
Number of Neutrons = (Mass number) - (Atomic Number)
Mass Number equals protons plus neutrons, round atomic weight to nearest whole number
Atomic Number equals number of Protons</span>
