Answer:
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
The right answer for the question that is being asked and shown above is that: "<span>b. number/timed." Reaction Rate refers to the </span> speed of reaction<span> for a reactant or product in a particular </span>reaction<span> is intuitively defined as how fast or slow a</span>re action<span> takes place.</span>
The relative volumes of chloroform and water that should be used is 9:10
Concentration of solution in chloroform =
( moles of chloroform )
Concentration of solution in water =
( moles of water )
Dissociation constant at
; 
Concentration of solution in chloroform / Concentration of solution in water
Meaning;

Since
mole is present in chloroform and
mole is present in water, Total mole of Caffeine present is 
Now, we substitute our given values into the equation

Therefore, the relative volumes of chloroform and water that should be used is 9:10
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