Which statements correctly describe the properties of air? Select three options.Air has mass but no weight.Air pressure is created by the weight of the atmosphere pushing on Earth’s surface.Pressure is a measure of how tightly molecules are packed.Denser air is heavier than less dense air.Air is less dense at higher altitudes.

The atmosphere’s weight pushes down on Earth’s surface, creating air pressure, so B is correct. For the same volume, denser air contains more mass and therefore weighs more than less dense air, making D correct. Air density generally decreases with altitude, so E is correct. Air has weight because gravity acts on its mass, and pressure is force per unit area—not simply a measure of how tightly molecules are packed.

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