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

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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