#1 not sure where to start. this is for ap physics!

First,

where is density, is mass, and is volume. We can compute the volume of the roll:

When the roll is unfurled, the aluminum will be a rectangular box (a very thin one), so its volume will be the product of the given area and its thickness . Note that we're assuming the given area is not the actual total surface area of the aluminum box, but just the area of the largest face (i.e. the area of one side of the unrolled sheet of aluminum).

So we have

where is the given area, so

If we're taking significant digits into account, the volume we found would have been , in turn making the thickness .

snell's law

refractve index = sin incidence / sin refraction