Question

How many moles are equal to 1.2 x 10^21 molecules of lithium?

Answer 1

1 mole --------------------------- 6.02 x 10²³ molecules
( moles lithium ) --------------- 1.2 x 10²¹ molecules

( moles lithium ) = (1.2 x 10²¹ ) x 1  / ( 6.02 x 10²³ )

= 1.2 x 10²¹ / 6.02 x 10²³

= 2.0 x 10⁻³ moles of lithium

Answer D

hope this helps!