This is earths science can anyone help me? I think I got it all wrong! I’m horrible with numbers.

Initially, the balloon had 3.0 liters of gas at a pressure of 400 kpa and was at a temperature of 294 k. if the balloon is cooled to 277 k and its volume decreased to 1 l, what will the new pressure in the balloon be?

Asingle atom of an element has 21 neutrons, 20 electrons, and 20 protons. which element is it? ok o z

What material does not melt at any temperature