A piece of chalk (CaCO3) has an initial mass of 43.5 grams. The massof the chalk decreased to 39.6 grams after it was used. Which of these is the closest value to the amount of chalk used?
The amount of chalk used can be calculated by finding the difference between the initial mass and the final mass:
43.5 grams - 39.6 grams = 3.9 grams
Therefore, the closest value to the amount of chalk used is 3.9 grams.