Question

liquid mercury has a density of 13.6 g/mL^-1. Which of the following substances will float on mercury, and which will sink?

neptunium 20.4 g/mL^-1
nickel 8.9
osmium 22.6
zinc 7.1
lead 11.4

Answer 1

Density = mass/volume. If something has a large mass compared to its volume, it has a high density.
The density of an object compared to the density of liquid it is placed in determining whether an object will sink or float.
An object that is less dense than mercury will float. So Nickel, Zinc, Lead float in liquid mercury.
An object that is denser than mercury will sink. Thus, Neptunium and Osmium sink in liquid mercury.