An increase in seawater density can be caused by which of the following?

• A. an increase in salinity
• B. a decrease in temperature
• C. a decrease in pressure
• D. an increase in volume

Answer: (A)

Verified step by step guidance

1. Understand that seawater density is defined as mass per unit volume, and it depends on factors such as salinity, temperature, pressure, and volume.
2. Recall that increasing salinity means adding more dissolved salts to the water, which increases the mass without significantly increasing the volume, thus increasing density.
3. Recognize that decreasing temperature generally causes water to contract, reducing volume and increasing density, so a decrease in temperature also increases density.
4. Note that decreasing pressure tends to allow water to expand slightly, increasing volume and decreasing density, so a decrease in pressure does not increase density.
5. Understand that an increase in volume, if mass remains constant, decreases density because density is mass divided by volume.