The first one
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<u>Answer:</u> The pH of the solution is 11.24
<u>Explanation:</u>
We are given:
Molarity of ammonia = 0.2 M

The given chemical equation follows:

I: 0.2
C: -x +x +x
E: 0.2-x x x
The expression for equilibrium constant follows:
![K_b=\frac{[NH_4^+][OH^-]}{[NH_3]}](https://tex.z-dn.net/?f=K_b%3D%5Cfrac%7B%5BNH_4%5E%2B%5D%5BOH%5E-%5D%7D%7B%5BNH_3%5D%7D)
Putting values in above expression, we get:

Neglecting the negative value of x as concentration cannot be negative.
So, ![[OH^-]=x=1.88\times 10^{-3}M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3Dx%3D1.88%5Ctimes%2010%5E%7B-3%7DM)
pOH is defined as the negative logarithm of hydroxide ion concentration present in the solution.
![pOH=-\log [OH^-]](https://tex.z-dn.net/?f=pOH%3D-%5Clog%20%5BOH%5E-%5D)
Putting values in above equation, we get:

We know:

Hence, the pH of the solution is 11.24
Halogens. Ex. fluorine can be the gas,bromine can be the liquid, and iodine could a solid all under room conditions.