Answer:
The correct answer is: pH= 4.70
Explanation:
We use the <em>Henderson-Hasselbach equation</em> in order to calculate the pH of a buffer solution:
![pH= pKa + log \frac{ [conjugate base]}{[acid]}](https://tex.z-dn.net/?f=pH%3D%20pKa%20%2B%20log%20%20%20%5Cfrac%7B%20%5Bconjugate%20base%5D%7D%7B%5Bacid%5D%7D)
Given:
pKa= 4.90
[conjugate base]= 4.75 mol
[acid]= 7.50 mol
We calculate pH as follows:
pH = 4.90 + log (4.75 mol/7.50 mol) = 4.90 + (-0.20) = 4.70
Here is the answer for the three of them
<span>N20 = 16 e-
</span><span>SeCl2 =20
</span><span>PBr3 = 26
Remember that t</span><span>o find the valence electrons in an atom you need to identify what group the element is in. An element in group 1A has 1 valence electron. If the element is in group 2A, then it has two valence electrons.</span>
We have to know final temperature of the gas after it has done 2.40 X 10³ Joule of work.
The final temperature is: 75.11 °C.
The work done at constant pressure, W=nR(T₂-T₁)
n= number of moles of gases=6 (Given), R=Molar gas constant, T₂= Final temperature in Kelvin, T₁= Initial temperature in Kelvin =27°C or 300 K (Given).
W=2.4 × 10³ Joule (Given)
From the expression,
(T₂-T₁)=
(T₂-T₁)= 
(T₂-T₁)= 48.11
T₂=300+48.11=348.11 K= 75.11 °C
Final temperature is 75.11 °C.