Density：練習題

What is the correct formula for calculating the density of a substance?

The formation of convection currents in the ocean is a result of changes in liquid density. Which of the following describes the correct sequence of this process?

Using particle theory, which of the following best explains why the density of sea water decreases as its temperature increases?

Which statement explains why colder ocean water generally lies beneath warmer ocean water?

When a river of fresh water flows into the salty ocean at an estuary, the fresh water often forms a layer on top of the sea water. Which statement best explains this phenomenon?

Using particle theory, state the effect of cooling a fixed mass of sea water on the movement of its particles and its resulting volume.

Explain why a body of water with a salinity of \(38\text{ ppt}\) will settle beneath a body of water with a salinity of \(34\text{ ppt}\) if both are at the same temperature.

The following data represents three sea water samples:
Sample A: mass \(102.5\text{ g}\), volume \(100.0\text{ cm}^3\)
Sample B: mass \(103.5\text{ g}\), volume \(100.0\text{ cm}^3\)
Sample C: mass \(101.5\text{ g}\), volume \(100.0\text{ cm}^3\)
Calculate the density of each sample and predict their vertical arrangement from top to bottom if placed in the same column.

A marine scientist is investigating how dissolved salts change the physical properties of water.

(a) Identify the independent variable in an experiment designed to investigate the effect of salt concentration on the density of seawater.
(b) The following data was collected for two samples:
Sample A: Mass = \(102.6\text{ g}\), Volume = \(100\text{ cm}^3\)
Sample B: Mass = \(104.5\text{ g}\), Volume = \(100\text{ cm}^3\)
Calculate the density of Sample B and state the correct units.
(c) Based on the data, state the relationship between salinity and the density of seawater.
(d) Use the density formula to calculate the mass of a \(500\text{ cm}^3\) volume of Sample A.

Density is a fundamental physical property of sea water that is influenced by temperature and salinity.
(a) A marine scientist collects a sea water sample with a mass of \(515\text{ g}\) and a volume of \(500\text{ cm}^3\). Calculate the density of this sample. Show your working and state the correct units.
(b) Explain the effect of increasing salinity on the density of sea water.
(c) Describe how differences in the density of water layers lead to the formation of convection currents.