Which of the following possess the greatest concentration of hydroxide ions?

a) a solution of ph 3.0

b) a solution of 0.10 m nh3

c) a solution with a poh of 12

d) a solution of 0.10 m naoh

e) a 1 x 10^-4 m solution of hno2

Answer : The correct option is (d) a solution of 0.10 M NaOH

Explanation :

(a) a solution of pH 3.0

First we have to calculate the pOH.

Now we have to calculate the concentration.

Thus, the concentration is,

(b) a solution of 0.10 M

As we know that 1 mole of is a weak base. So, in a solution it will not dissociates completely.

So, the concentration will be less than 0.10 M

(c) a solution with a pOH of 12.

We have to calculate the concentration.

Thus, the concentration is,

(d) a solution of 0.10 M NaOH

As we know that is a strong base. So, it dissociates to give ion and ion.

So, 0.10 M of in a solution dissociates to give 0.10 M of ion and 0.10 M of ion.

Thus, the concentration is, 0.10 M

(e) a solution of

As we know that 1 mole of in a solution dissociates to give 1 mole of ion and 1 mole of ion.

So, of in a solution dissociates to give of ion and of ion.

The concentration of ion is

First we have to calculate the pH.

Now we have to calculate the pOH.

Now we have to calculate the concentration.

Thus, the concentration is,

From this we conclude that, a solution of 0.10 M NaOH possess the greatest concentration of hydroxide ions.

Hence, the correct option is (d)