Final answer:
The mass gained can be calculated by finding the difference between the mass before and after the tablet reacts with water.
Step-by-step explanation:
To find the mass gained, we need to calculate the difference between the mass before and after the tablet reacts with water. Let's assume the mass before the reaction is 5 grams and the mass after the reaction is 8 grams. The mass gained would be 8 grams - 5 grams = 3 grams. Therefore, the correct answer is C. 3.32 grams.