What is the percent composition by mass for sodium (Na) in sodium phosphate (Na3PO4)? % Na = (_/_)x100% = _% NNA

please help.

The pressure inside a hydrogen-filled container was 2.10 atm at 21 ? c. what would the pressure be if the container was heated to 92 ? c ?

What state of matter is ice a. liquid b. element c. solid d. gas

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 ?