How can anyone answer your questions when you leave out most of the units?

Sigh. I'm sorry, when I pasted the questions it left out the units for some reason. Nothing has been working for me today. Thank you for pointing it out.

FIXED VERSION:

1) "1 mole of sand grains would cover the state of Texas to several feet. Estimate how many feet by assuming that the sand grains are roughly cube-shaped, each one with an edge length of 0.10 mm. Texas has a land area of 268,601 square miles."

I repeatedly got a large number of ft, and it doesn't make sense to me at all. This is what I did:

.001mm^3*(Avogadro's number)=6.022*10^20 mm^3

1ft^3/304.8^3 = x/6.022*10^20 mm^3, where x=2.12664923*10^13 ft^3

the square root of 2.12664923*10^13 ft^3 is 4611560.723 ft, but that still doesn't make any sense.

2) "Lead metal can be extracted from a mineral called galena, which contains 86.6 % lead by mass. A particular ore contains 68.5 % galena by mass. If the lead can be extracted with 92.5 % efficiency, what mass of ore is required to make a lead sphere with a 4.50 cm radius? Express your answer with the appropriate units."

I ended up (after a bunch of conversions) with 666.8495375 g of ore(using 100 g of galena and ore to start with to make calculations easier). Did I do it right?

3) "Mercury is often used as an expansion medium in a thermometer. The mercury sits in a bulb on the bottom of the thermometer and rises up a thin capillary as the temperature rises. Suppose a mercury thermometer contains 3.450 g of mercury and has a capillary that is 0.200 mm in diameter. How far does the mercury rise in the capillary when the temperature changes from 0.0 °C to 25.0 °C ? The density of mercury at these temperatures is 13.596 g/cm^3 and 13.534 g/cm^3 , respectively.

Express your answer with the appropriate units."

This one I couldn't even figure out how to approach. I went back to it after the test was over and still couldn't figure it out.