Question

speed of sound in seawater (\\(\frac{\text{m}}{\text{s}}\\)) 1,449 1,490 1,522 1,546
which statement can be inferred about the speed of sound in freshwater and in seawater?
(1 point)
\\(\circ\\) at \\(80^\circ\text{c}\\), the speed of sound in freshwater and seawater will be the same.
\\(\circ\\) the speed of sound increases as the salinity of water decreases.
\\(\circ\\) the speed of sound increases as the density of water increases.
\\(\circ\\) both temperature and salinity decrease the speed of sound in water.

Explanation:

1. Analyze Option 1: At 80°C, freshwater and seawater (different salinity) have different densities and properties, so sound speeds won’t be the same. Eliminate.
2. Analyze Option 2: Seawater has higher salinity than freshwater. The given seawater speeds (1449, 1490, 1522, 1546 m/s) are generally higher than typical freshwater sound speeds (e.g., ~1500 m/s at 20°C, but trends: higher salinity (seawater) relates to higher density and higher sound speed). So "speed increases as salinity decreases" is wrong (salinity decrease would mean moving to freshwater, which has lower sound speed than seawater in trend? Wait, actually, sound speed in water depends on density (and temperature). Seawater is denser than freshwater. So if density increases (with salinity, or temperature), sound speed increases. So Option 2 is incorrect.
3. Analyze Option 3: Seawater is denser than freshwater. The speed of sound in seawater (given values) and knowing that denser media (for water, within liquid phase) transmit sound faster (since sound speed in liquids: \( v \propto \sqrt{\frac{B}{

ho}} \), but bulk modulus \( B \) also increases with density in water; net effect: higher density (seawater) has higher sound speed than freshwater. So as density increases (seawater vs freshwater, or with salinity/temperature increasing density), sound speed increases. This matches.

1. Analyze Option 4: Temperature increase increases sound speed in water (molecules vibrate faster, easier to transmit), and salinity increase (seawater) increases density (and bulk modulus) leading to higher sound speed. So "both decrease speed" is wrong.

Thus, the correct statement is "The speed of sound increases as the density of water increases."

Answer:

The speed of sound increases as the density of water increases.