there are 2 questions please help.

20. A compound is composed of only C and H. It contains 88.82%C by mass and has a molar mass of 54.09g/mol. What is its empirical formula? Show calculations for credit 21. When lead (II) nitrate reacts with sodium iodide, sodium nitrate and lead (II) iodide are formed. a. Balance the following equation: Pb(NO3)2(aq)+NaI()PbI2(3)+NaNO3() b. If you start with 25.0 grams of lead (II) nitrate and 15.0 grams of sodium iodide, how many grams of lead(II)iodide can be formed? Show calculations for credit c. What is the limiting reagent in the reaction? d. How much of the nonlimiting reagent or excess reagent will be left over from the reaction? Show calculations for credit e. If 6 grams of lead(II)iodide are formed in the reaction described in problem, what is the percent yield of this reaction? Show calculations for credit