Density, Temperature, and Salinity

What does analyzing the salinity of sea water help determine?

• The clarity of sea water

• The biodiversity in sea water

• The salt content in sea water

• The pollution levels in sea water

Answer explanation

Determining the concentration of salt in ocean water allows students to measure the amount of salt in the water accurately.

How does changing temperature affect the density of lake water?

• Higher temperatures increase water density

• Lower temperatures increase water density

• Temperature has no effect on water density

• Temperature only affects the color of water

Answer explanation

Lower temperatures increase water density

Tags

NGSS.MS-PS1-4

What unit is commonly used to measure the salt concentration of seawater?

• Celsius

• Pounds

• Parts per thousand (ppt)

• Liters

Answer explanation

The salt concentration of seawater is commonly measured in parts per thousand (ppt).

Why do lakes freeze from the top during winter, allowing fish to survive underneath?

• The top layer is colder than the bottom layer

• Water expands upon freezing, reducing its density

• The ice layer has a higher salinity than the water below

• The ice layer acts as an insulator, absorbing heat from the water below

Answer explanation

Lakes freeze from the top because water expands upon freezing, reducing its density. This allows fish to survive underneath.

Tags

NGSS.MS-PS1-4

When seawater has higher salinity, what happens to its density?

• It decreases

• It increases

• It stays the same

• It first increases, then decreases

Answer explanation

When seawater has higher salinity, its density increases.

At what temperature does freshwater reach its maximum density?

• 0°C

• 4°C

• 100°C

• 25°C

Answer explanation

Freshwater reaches its maximum density at 4°C, making it the correct choice. This temperature allows water molecules to arrange in a way that maximizes their packing, resulting in higher density.

Which factor does NOT affect the salinity of ocean water?

• Evaporation

• Freezing of ice

• Rainfall

• The color of the ocean floor

Answer explanation

The salinity of ocean water is not affected by the color of the ocean floor. Factors such as evaporation, freezing of ice, and rainfall contribute to changes in salinity.

How does the salinity of ocean water typically change from the equator to the poles?

• Increases towards the poles

• Decreases towards the poles

• Stays the same

• First increases, then decreases

Answer explanation

The salinity of ocean water typically decreases from the equator to the poles. This is due to the melting of ice and the addition of freshwater from rivers.

What effect does water temperature have on its ability to dissolve salt in a saltwater aquarium?

• Higher temperatures increase its ability to dissolve salt

• Lower temperatures increase its ability to dissolve salt

• Temperature has no effect on its ability to dissolve salt

• Only extremely high temperatures increase its ability to dissolve salt

Answer explanation

Higher temperatures increase salt dissolution in water.

Tags

NGSS.MS-PS1-4

Why is the Dead Sea so salty?

• It has a lot of fish

• It is very deep

• High evaporation rates and low freshwater inflow

• It is located at the North Pole

Answer explanation

The Dead Sea is so salty due to high evaporation rates and low freshwater inflow, which leads to a high concentration of minerals and salt in the water.