Can someone help me to answer this correctly, please, and explain it. Please answer these 3 short questions, I don't have more money to buy more questions. These 3 questions are different.

1. a.

1. b.

1. c.

A sample of a gaseous binary compound of boron and fluorine weighing 0.457g is decomposed to give 7.29102g of solid B. In a separate experiment, the molar mass of the compound is determined to be 67.8g/mol. Determine the molecular formula of the compound. Enter B before F. A solution is made by dissolving 13g of zinc nitrate, Zn(NO3)2, in enough water to make exactly 500mL of solution. Calculate the concentration (molarity) of Zn(NO3)2 in mol/L(M). MZn(NO3)2 Calculate the mass, in grams, of Zn(NO3)2 required to prepare exactly 500mL of a 0.400M solution of Zn(NO3)2