Final answer:
To find the mass of salt added to the beaker, subtract the mass of the empty beaker (750 g) from the total mass (1080.6 g), resulting in 330.6 g. The correct answer rounded to significant figures is 331 g.
Step-by-step explanation:
The mass of the salt added to an empty beaker can be found by subtracting the mass of the empty beaker from the total mass after the salt has been added. In this case, the total mass with the salt is 1080.6 g, and the mass of the empty beaker is 750 g. Using the correct significant figures, we subtract 750 g from 1080.6 g to get the mass of the salt.
1080.6 g - 750 g = 330.6 g
However, since we must report our answer with the same number of decimal places as the measurement with the least number of decimal places, and the empty beaker's mass (750 g) has no decimal places, we round the mass of the salt to the nearest whole number, giving us 331 g as the correct answer.