A student needs to prepare 50.0 mL of a 0.90 M aqueous H2O2 solution. Calculate the volume of 4.9 M H2O2 stock solution that should be used to prepare the solution.

Well technically there are two correct answers b and d. but for you its probably b in general.good day sir/ma'am : ) (i know not gender)

1) according to the law of conservation of mass ,in all chemical reactions total mass is unchanged

Answerδh > 0explanationc₆h₆  (s)  → c₆h₆ (l)if you are changing it from a solid to a liquid, you are pretty much melting the solid. this requires heat energy. therefore, the reaction is endothermic (takes in energy); the system enthalpy increases as the reaction proceeds: δh > 0.