155.0 mL x 0.274 M SO42- reacts with 155.0 x 0.274 * 2 (Ag+/SO42-) = 84.94 mmol Ag+

84.94 mmol Ag+ is in 84.94 (mmolAg+) / 0.305 (M Ag+) = 84.94/0.305 = 278.5 mL of 0.305 M Ag+.

Na+ and NO3- are tribuned out of this reaction.

The amount of moles is also defined as n = m/M, where

n - amount of moles,

m - the mass of the substance,

M - the atomic mass of the substance (Ag - 107.8682 g/mol), therefore

m = n×M = 0.263×107.8682 = 28,369 grams of Ag.

42 km = 42 000 m

TO convert from km to m, multiply by 1000.