To find the mass of phosphoric acid (H₃PO₄), you should (1) convert molecules to moles (via Avogadro's number) and then (2) convert moles to grams (via molar mass from periodic table).
6.534 x 10²⁴ molecules H₃PO₄ 1 mole 97.99 g --------------------------------------------- x ------------------------------------- x -------------- 6.022 x 10²³ molecules 1 mole
if you search up the periodic table and go to any website it will let you press on the element and it will say if it is a gas,solid or liquid and it might say if it is man made!