How many molecules are there in a 3.46-g sample of HCl?
(a) 6.022 x 1023 molecules
(b) 5.71 x 1022 molecules
(c) 9.48 x 1023 molecules
(d) 36.46 molecules

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 ?