how many mass of hydrogen gas will be liberated when 6g of magnesium dissolves in 250cm^3 and 6mol/dm^-3 of HCL

Acompound contains c, h, and o atoms. when 1.130 g of the compound is burned in oxygen, 1.064 g co2 and 0.3631 g h2o are produced. what is the empirical formula of this compound?

The mass of a neutron is equal to the mass of a proton plus the mass of an electron. true or false false true

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 ?