Question

The mass of an unidentified rock is 40 grams. Students determine the volume of the rock by placing the rock in a cylinder with water. The students calculate the density of the rock. They determine the identity of the rock based on the density ranges in the table.

Answer 1

A. Coal

Step-by-step explanation:

`Volume_(rock)` = water displaced by rock

Water displaced by rock = volume of water after rock is dropped into the cylinder - volume of water before the rock was dropped into the water

Water displaced by the rock = 180 ml - 150 ml = 30 ml

`Volume_(rock) = 30 ml`

Density of rock:

40 grams => 30 ml

x grams => 1 ml

Cross multiply

1*40 = 30*x

40 = 30x

40/30 = 30x/30

1.3 = x

Density of rock = 1.3 g per 1 ml

Recall: 1 ml = 1 cm³

Therefore,

Density of the rock = 1.3 g/cm³

1.3 g/cm³ falls within the range of 1.1 - 1.4 g/cm³

Therefore, the rock is identified as Coal.