Read this for the next two problems: When a 125 g obsidian rock is placed into a graduated cylinder, the water level rises from the 15 mL to the 47 mL mark.
29. What is the rocks volume?
a) 62 mL
b) 32 mL
c) 15 mL
d) 47 mL
30. What is the rocks density?
a) 0.25 g/mL b) 1 g/mL
c) 2.0 g/mL d) 3.9 g/mL
31. If you add a mass of 3.7 g to a mass of 9.495 9. the sum with the correct number of
significant digits is
a) 13.29 b) 13.209 c) 13.199 d) 13.1959

29. Option (b) 32 mL

30. Option (d) 3.9 g/mL

31. Option (d) 13.195 g

Explanation:

29. Determination of the volume of the rock.

Volume of water = 15 mL

Volume of water + Rock = 47 mL

Volume of Rock =.?

Volume of Rock = (Volume of water + Rock) – (Volume of water)

Volume of Rock = 47 – 15

Volume of Rock = 32 mL

30. Determination of the density of the rock.

Density of a substance is simply defined as the mass of the substance per unit volume of the substance. It can be represented mathematically as:

Density (D) = mass (m) /volume (V)

D = m/V

With the above formula, the density of the rock can be obtained as follow:

Mass (m) of Rock = 125 g

Volume (V) of Rock = 32 mL

Density (D) =?

D = m/V

D = 3.9 g/mL

Therefore, the density of the rock is 3.9 g/mL.

31. Determination of the sum of 3.7 g and 9.495 g.

The sum of 3.7 g and 9.495 g can be obtained as follow:

3.7 g + 9.495 g = 13.195 g