Final answer:
For whipping 1 egg white, 1 teaspoon of lemon juice or vinegar is needed. The pH increase in hydrogen ion concentration between tomato juice at pH 4.0 and lemon juice at pH 2.0 is 100 times.
Step-by-step explanation:
The question: How much lemon juice or vinegar is needed when whipping 1 egg white? This is a culinary question, and the answer is (a) 1 teaspoon. However, to explain the pH-related question about the increase in hydrogen ion concentration between tomato juice and lemon juice, we must understand the pH scale which is logarithmic. This means that each whole pH value below 7 is ten times more acidic than the next higher value. Therefore, a pH value moving from 4.0 to 2.0 (the pH of tomato juice to lemon juice) represents a 100-fold increase in acidity, because it covers a 2-point decrease: 10 times for the first point and 10 times again for the second point, hence 10 x 10 = 100 times.
So, the correct answer to the pH question is (c) 100 times.