How many grams of silver oxide are needed to react with 7.9 g of hydrochloric acid produce silver chloide and water?

25.11 g.

Explanation:

Ag₂O + 2HCl → 2AgCl + H₂O.

that 1.0  mole of Ag₂O reacts with 2.0 moles of HCl to produce 2.0 mole of AgCl and 1.0 moles of H₂O.

no. of moles of HCl = mass/atomic mass = (7.9 g)/(36.46 g/mol) = 0.2167 mol.

∴ 0.2167 mol of HCl will react with (0.2617 mol / 2 = 0.1083 mol) of Ag₂O.

∴ The mass of reacted Ag₂O = no. of moles x molar mass = (0.1083 mol)(231.735 g/mol) = 25.11 g.

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)