The answer is “Family”
Explanation- There are 18 numbered groups in the periodic table. The elements in a group have similar physical or chemical characteristics and some groups have a specific name, for example group 17 (the halogens).
At the highest point: kinetic energy is 0 due to the speed is 0
So the total mechanical energy is 20
Assume no frictions present, then the mechanical energy is conserved
So at the lowest point, kinetic energy = mechanical energy - potential energy
Answer will be 20 - 0.5 = 19.5 J