I wasted my time, pls help me with this again

Select the word from the list that best fits the definition classification of most stars on the h-r diagram

Ryan is examining the energy of the particles in a bar of gold. what is ryan most likely studying?

On your wedding day your lover gives you a gold ring of mass 3.67 g. 48 years later its mass is 3.44 g. on the average how many atoms were abrated from the ring during each second of your marriage? the atomic mass of gold is 197 u. don't enter units