0.600 moles of BF3 is how many molecules of BF3?

What does a numerical subscript following an element in a chemical formula mean?

Calculate the ph at the equivalence point for the titration of a solution containing 150.0 mg of ethylamine (c2h5nh2) with 0.1000 m hcl solution. the volume of the solution at the equivalence point is 250.0 ml. kb forethylamine is 4.7 × 10−4 .

Johnny's bakery has 30,900 grams of sugar. a recipe calls for 32 pounds of sugar to be used. how much sugar will be left over? (1 lb=453.59 g).