A measuring cylinder resting on an electronic balance contains a liquid as shown in diagram 1. A small solid object X is gently lowered into the liquid and no liquid splashes out of the cylinder. The result is shown in diagram 2.
What is the density of the material from which object X is made?

Answer:

7) C

When the object is gently lowered, here are the changes that take place: The scale changes from 750 g to 950 g. So mass of object = 200 g
The liquid rises from 375 cm3 to 500 cm3.
Volume of object = 125 cm3
Density = Mass ÷ Volume = 200 ÷ 125 = 1.6 g cm-3