A gas mixture is composed of 4.3 grams of hydrogen (density at STP= 0.089g/L) and 2.9grams of helium ( density at STP = 0.179 g/L). What is the percentage (v/v) helium in the mixture? SHOW WORK

Compare and contrast physical changes with chemical changes.

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 ?

If i had 2 m naoh solution, what does the 2 m stand for? 2 molar, but 2 of a solute in 1