How many molecules of Helium are in 1.0 mole?

Explain that newton first law,second law and third law of motion?

650.j is the same amount of energy as? 2720cal1550cal650.cal2.72cal

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 ?