Yes, gas molecules have weight because they have mass. The weight of a gas molecule is determined by its mass and the force of gravity acting on it.
Gravity affects gas molecules by pulling them towards the center of the Earth. This causes gas molecules to have a higher concentration near the surface of the Earth and a lower concentration at higher altitudes.
In a uniform gravitational field, gas molecules do not align with gravity. This is because gas molecules are in constant motion and their random movements prevent them from aligning with the direction of gravity.
No, gas molecules cannot defy gravity. However, they can appear to defy gravity in certain situations, such as when they are in a container with a lower density gas or in a low gravity environment like outer space.
Temperature does not affect the alignment of gas molecules with gravity. However, it can affect the speed and movement of gas molecules, which in turn can affect their distribution in a gravitational field.