What is the pH of this solution?

pH = 11.216.

Explanation:

Hello there!

In this case, according to the ionization of ammonia in aqueous solution:

We can set up its equilibrium expression in terms of x as the reaction extent equal to the concentration of each product at equilibrium:

However, since Kb<<<1 we can neglect the x on bottom and easily compute it via:

Which is also:

Thereafter we can compute the pOH first:

Finally, the pH turns out:

Regards!

a electronegativity decreases beacuse the size of nucleus is bigger.