Which of the following best describes the effect of increasing salinity on the density of water?

• A. Increasing salinity increases the density of water.
• B. Increasing salinity first increases and then decreases the density of water.
• C. Increasing salinity decreases the density of water.
• D. Salinity has no effect on the density of water.

Answer: (A)

Verified step by step guidance

1. Understand that density is defined as mass per unit volume, given by the formula \(\rho = \frac{m}{V}\), where \(\rho\) is density, \(m\) is mass, and \(V\) is volume.
2. Recognize that salinity refers to the concentration of dissolved salts in water, which adds mass without significantly increasing the volume of the water.
3. Consider that when salt dissolves in water, it increases the total mass of the solution while the volume increases only slightly, leading to an overall increase in density.
4. Recall that this effect is why seawater, which has higher salinity than freshwater, is denser and objects float more easily in it.
5. Conclude that increasing salinity increases the density of water because the added dissolved salts increase the mass more than the volume.