Which among the following represent a set of isotopes? Atomic suclei containing:
L. 20 protons and 20 neutrons
II. 21 protons and 19 neutrons
III. 22 neutrons and 18 protons
IV. 20 protons and 22 neutrons
V. 21 protons and 20 neutrons
No isotopes are indicated.
I. V
1, II, III
I, IV and II, V
III. IV