How many molecules of water are in a collection of snowflakes with a mass of 0.005 grams?

Question

A) 5.43 x 10²²

B) 3.01 x 10²⁴

C) 1.67x 10²⁰

D) 2.17 x 10²¹

Answer 1

Assuming the snowflake has nothing in it other than water...

0.005 grams H2O x 1 mol H2O/18 g x 6.02x10²³ molecules H2O/mole H2O = 1.67x10²⁰ molecules of H2O

ANSWER C (even though it has an incorrect number of significant figures)