Whats the mass of 3.05x10^23 atoms of oxygen

Neils bohr believed that electrons orbited the nucleus in different energy levels, based on strong support from

A50.0g sample of liquid water at 0.0 c ends up as ice at -20.0 c. how much energy is involved in this change?

Mercury turns to vapor at 629.88 k how much heat is lost 175 g of mercury vapor at 650 current condenses to a liquid at 297 ca mercury turns to weber at 629.88 kelvin how much he is lost 175 g of mercury vapor and 650 coming condensers to liquidate 297 kevin