Question

One mole of sand would cover the state of California to several feet. Estimate how many feet by assuming that the sand are roughly cube shaped each with an edge length of 0.10mm California has a land area of 163,696 square miles.

Answer 1

For the answer to the question above,  volume of 1 sand grain = (0.10 mm)³ = 0.001 mm³ 

1 mole sand x (6.02214x10^23 grains / mole) x (0.001 mm³ / grain) = 6.02214x10^20 mm³ 

268,601 mi² x (5280 ft / mi)² x (12 in / ft)² x (2.54 cm / in)² x (10 mm / 1 cm)² = 6.95673x10^17 mm² 

V = height x area 
height = V / A = 6.02214x10^20 mm³ / 6.95673x10^17 mm² = 865.657 mm 

finally... 
865.657 mm x (1 cm / 10 mm) x (1 in / 2.54 cm) x (1 ft / 12 in) = 2.84008 ft.
= 6 sig figs.