The answer is b. radon-222. The alpha decay means that it will emit an alpha particle when decays. The alpha particle has two protons and two neutrons. So Radium(88) minus two protons will become Radon(86). And the atomic mass will become 226-4=222.
Answer:
Lithium, Potassium and Calcium
Explanation:
Because they are all in group one of the periodic table
if density = m(mass) / v(volume) then the answer would be 3
