What is true about the two numbers in a conversion factor?

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 ?

When the mercury level in a barometer decreases that atmospheric pressure has

What physical property of gold makes panning a useful way to get gold from streams?