One crystalline form of silica (SiO2) has a cubic unit cell, and from X-ray diffraction data it is known that the cell edge length is 0.700 nm. If the measured density is 2.32 g/cm3, how many (a) Si4 and (b) O2- ions are there per unit cell

There are 8Si atoms and 16 O atoms per unit cell

Explanation:

From the question we are told that:

Edge length

Density

Generally the equation for Volume is mathematically given by

Where

Molar mass of  (SiO2) for one formula unit

Therefore

Density of Si per unit length is

Molar mass of  (SiO2) for one formula unit

Therefore

There are 8Si atoms and 16 O atoms per unit cell

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.

it would be b. 6co2 + 6h2o --> c6h12o6 + 6o2