1.2×1021.atoms Li=2.0×10−3.mol Li.
Step-by-step explanation:
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)