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
Answer:
pH = 6.82
Explanation:
To solve this problem we can use the<em> Henderson-Hasselbach equation</em>:
- pH = pKa + log
![\frac{[NaOCl]}{[HOCl]}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BNaOCl%5D%7D%7B%5BHOCl%5D%7D)
We're given all the required data to <u>calculate the original pH of the buffer before 0.341 mol of HCl are added</u>:
- pKa = -log(Ka) = -log(2.9x10⁻⁸) = 7.54
- [HOCl] = [NaOCl] = 0.500 mol / 0.125 L = 4 M
- pH = 7.54 + log

By adding HCl, w<em>e simultaneously </em><u><em>increase the number of HOCl</em></u><em> and </em><u><em>decrease NaOCl</em></u>:
- pH = 7.54 + log
![\frac{[NaOCl-HCl]}{[HOCl+HCl]}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BNaOCl-HCl%5D%7D%7B%5BHOCl%2BHCl%5D%7D)
- pH = 7.54 + log

Answer:
The move from Level n=3 to Level n=2 has the long wavelength.
Explanation:
First, due to the selection rules, only transitions between adjacent levels are allowed, thus, only a transition between Level n=3 to Level n=2 or Level n=5 to Level n=4 are allowed. The two first options are wrong.
Second, analyzing the transition between Level n=3 to Level n=2 and the transition between Level n=5 to Level n=4 it is necessary to think in terms of the equation of the difference of energy for these type of transitions:
Δ
(1)
The difference in energy (ΔE) is directly proportional to the quadratic difference between the 'n' levels of transition. Therefore, If the transition occurs between smaller 'n' levels the difference of energy will be smaller too.
Also, the energy (ΔE) is inversely proportional to the wavelength (λ) so a smaller energy means a larger wavelength.
ΔE = c / λ (2)
Hence, the move from Level n=3 to Level n=2 has a long wavelength.
In order to calculate this wavelength is necessary to replace the data on equation (1) and (2).
Answer : The solubility of
in water is, 
Explanation :
The solubility equilibrium reaction will be:

Let the molar solubility be 's'.
The expression for solubility constant for this reaction will be,
![K_{sp}=[Ag^{+}]^3[PO_4^{3-}]](https://tex.z-dn.net/?f=K_%7Bsp%7D%3D%5BAg%5E%7B%2B%7D%5D%5E3%5BPO_4%5E%7B3-%7D%5D)


Given:
= 
Now put all the given values in the above expression, we get:



Therefore, the solubility of
in water is, 