Answer:
Alpha particle
Explanation:
An alpha particle is a helium nucleus, 2 protons and 2 neutrons, loss of an alpha particle give a new element with an atomic number 2 less than the original isotope and an atomic mass that is lower by about 4 amu.
the answer is b Li + Cl2 .....
D. Valance Electrons
20 protons and 20 electrons