Sally's teacher tells her to find the masses of a sugar cube and a glass of water. Sally finds the masses to be 10 g for the sugar cube and 100 g for the glass of water. Then, the teacher tells her to put the sugar cube into the water. Sally puts the cube into the glass of water and watches as it dissolves. Then, the teacher tells Sally to estimate the new mass of the glass of sugar-water.

Question

What should Sally guess as the new mass of the glass of sugar-water?
A.
110 g
B.
90 g
C.
50 g
D.
200 g

Answer 1

When Sally puts the sugar cube into the glass of water, the mass of the sugar cube (10 g) is added to the mass of the water (100 g). The mass of the glass of sugar-water is the sum of the masses of the water and the dissolved sugar, since mass is conserved.

So, the new mass can be calculated as follows:

Mass of water = 100 g
Mass of sugar = 10 g
Total mass = 100 g + 10 g = 110 g

Therefore, Sally should guess that the new mass of the glass of sugar-water is:

A. 110 g