How is the scientific definition of "heat" different from how we use it every day? need the answer asap

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?

How will the volume of a gas be affected if the pressure is tripled, but the temperature remains the same?

Which element is least likely to undergo a chemical reaction