Multimeters are used to test the conductivity of a substance. What is most likely the identity of the liquid?

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 could a student test the effect of removing heat from a gas that is stored in a sealed container? what must occur in order for matter to change states?

How many moles are in 7.2 x 10^23 carbon molecules?