How many moles are equal to 1.2 x 1021 molecules of lithium?

1.2×1021.atoms Li=2.0×10−3.mol Li.

Lithium is a metal. It does not exist as molecules. We can, however, determine the moles equal to 1.2×1021 atoms of lithium.

1 mol atoms=6.022×1023 atoms

1.2×1021atoms Li×1mol Li atoms6.022×1023atoms Li=2.0×10−3mol Li (rounded to two significant figures)

your answer would be a. 12.5 kg

d.) the average kinetic energy of the gas particles is greater in container b because its particles move faster.