Why is it better to use several trials of a titration rather than one trial to determine the concentration of a solution of unknown concentration?

Suppose you got a low yield of benzoin from your benzoin condensation reaction and thus only have 0.300 g of benzoin to use as the starting material for this reaction. how much concentrated nitric acid should you add? (concentrated nitric acid is 15.8 m). write your answer in the form x.xx ml

Used the balanced equation 2h2+ o2 - -> 2h2o. if you have 7.2 grams of o2 , how many grams of h2o can you produce ?

What happened in 2012 and how does it illustrate the importance of understanding the sun and how it works?