Question

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

Explanation:

Step1: Recall pH - OH⁻ relationship

The higher the pH, the lower the hydrogen - ion ($H^+$) concentration and the higher the hydroxide - ion ($OH^-$) concentration.

Step2: Compare pH values

We have baking soda (pH = 9), milk (pH = 6), tomato juice (pH = 3.5), and vinegar (pH = 2). Baking soda has the highest pH among them.

Answer:

baking soda, pH = 9