What information is needed to calculate the percent composition of a compound

The following reaction shows sodium carbonate reacting with calcium hydroxide. na2co3 + ca(oh)2 → naoh + caco3 how many grams of naoh are produced from 20.0 grams of na2co3? (molar mass of na = 22.989 g/mol, c = 12.01 g/mol, o = 15.999 g/mol, ca = 40.078 g/mol, h = 1.008 g/mol) 12.2 grams 15.1 grams 24.4 grams 30.2 grams

At 300 mm hg, a gas has a volume of 380 l, what is the volume at standard pressure

The diagram below shows the different phase transitions that occur in matter. which arrow represents the transition in which dew is formed?