Question

the air temperature is 70 degrees, and the relative humidity is 90%. which conclusion can be made? (1 point)
the air holds little water vapor and is relatively dry.
the dew point temperature is 90% of the air temperature.
the amount of water vapor in the air is 90% of what the air can hold.
the temperature must rise in order for air to become saturated with water vapor.

Explanation:

Relative humidity is defined as the ratio of the amount of water vapor present in the air to the maximum amount of water vapor the air can hold at a given temperature, expressed as a percentage. So, if the relative humidity is 90%, it means the amount of water vapor in the air is 90% of what the air can hold.
The first option is incorrect because high relative humidity (90% is relatively high) means the air holds a significant amount of water vapor, not little.
The dew - point temperature is not calculated as a percentage of the air temperature. The dew - point is the temperature to which air must be cooled to become saturated with water vapor.
For the fourth option, to become saturated (reach 100% relative humidity), if the amount of water vapor is constant, the temperature should decrease (since cooler air can hold less water vapor), not rise.

Answer:

The amount of water vapor in the air is 90% of what the air can hold.