An ionic compound forms when a metal bonds with a non-metallic element. Metals usually form the cation and non-metal anions. Chromium has an oxidation number of +3 in the compound and charge on hydroxide ion is -1.
Cation here is 
Anion is the hydroxide ion 
So the formula of the compound will be: 
. The compound has one chromium atom and two hydroxide ions.
Therefore, there will be one Chromium atom per each chromium hydroxide compound.
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
Answer is A
All elements on the periodic table have a different number of protons that can be represented by its atomic number
I think it’s C but anybody can correct me if I’m wrong
