I believe you can simply add more cells in series to get a higher voltage. Not 100% sure on that.
Answer : The pH of a 0.1 M phosphate buffer is, 6.86
Explanation : Given,

Concentration of acid = 0.1 M
Concentration of conjugate base (salt) = 0.1 M
Now we have to calculate the pH of buffer.
Using Henderson Hesselbach equation :
![pH=pK_a+\log \frac{[Salt]}{[Acid]}](https://tex.z-dn.net/?f=pH%3DpK_a%2B%5Clog%20%5Cfrac%7B%5BSalt%5D%7D%7B%5BAcid%5D%7D)
Now put all the given values in this expression, we get:


Therefore, the pH of a 0.1 M phosphate buffer is, 6.86
The answer is D. obsidian. Or at least I think it is. Just guessing based off me playing Minecraft 6 years ago haha
Answer:
The elements in each group have the same number of electrons in the outer orbital. Those outer electrons are also called valence electrons.
Explanation: