A group of students investigated the effect of soaking small onion bulbs in different concentrations of sodium chloride solution. They peeled off the outer papery leaves of the onion bulbs and divided
the onions into 6 batches, each with 10 onions.
The onions were surface dried with paper towels and weighed. The mean mass of the onions in
each batch was calculated. The onions were then left in sodium chloride solutions for three hours.
After three hours the students surface dried the onions and weighed them again. Their results are
given in Table 2.1.

Calculate the percentage change in mass of the onions that were in the most concentrated solution of sodium chloride. Show your work. Write your answer in Table 2.1.

Explain why the students calculated the percentage change in mass of the onions.