A balloon filled with air has a volume of 4.24 liters at 23.00°C. If the balloon is cooled at constant pressure to 5.00°C, what is its new volume?

The new volume will be

0.7 L

Explanation:

This is an example of Charles' law, sometimes called the temperature-volume law. It states that the volume of a gas is directly proportional to the Kelvin temperature, while pressure and amount are held constant.

altitude, density, pressure

air gets less dense the higher the altitude and also the air pressure is less as altitude rises.

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)