#### Answer

2.84 ft

#### Work Step by Step

find total volume of 1 mol sand grain and divide by area of TX to get height. Pay attention to Units:
volume of 1 sand grain= (0.10mm)^3= 1.0 x 10^-3 mm3
1 mole =6.023 x 10^23
Total volume of sand = (6.023 x10^23) x(1.0 x10^-3 mm3)
= 6.023 x10^20 mm3
convert to ft:
1inch=25.4 mm so 12in (1 ft) = 12 x 25.4 mm = 304.8 mm
Express volume of sand in ft3
(6.023 x10^20 mm3) x ((1 ft)^3)/((304.8mm)^3) = 2.127 x10^13 ft3
convert miles to ft -- 1 mile =5280 ft
finally divide volume of sand by area:
Height
= ((2.127 x 10^13 ft3)/(268,601 miles^2)) *((1 mile^2)/(5280^2 ft2))
Height =2.84 ft