Which solution has the greatest number of hydroxide ions? baking soda, pH = 9milk, pH = 6tomato juice, pH = 3.5vinegar, pH = 2

Answer: -

Baking soda having a pH of 9, has the maximum number of hydroxide ions.

Explanation: -

More the pH of a solution, the more basic it is and more the number of hydroxide ions it has.

From the question we find that

baking soda has a pH = 9

milk has a pH = 6

tomato juice has a pH = 3.5

vinegar has a pH = 2

Thus among them baking soda has the highest pH.

So baking soda is the most basic and has the maximum number of hydroxide ions.

Answer: is A, baking soda, pH = 9