Which of the following is a method of purifying water

An aqueous solution of hydroiodic acid is standardized by titration with a 0.186 m solution of calcium hydroxide. if 26.5 ml of base are required to neutralize 20.3 ml of the acid, what is the molarity of the hydroiodic acid solution? m hydroiodic acid

If i make a solution by adding 83grams of sodium hydroxide to 750ml i’d water what is the molarity of sodium hydroxide

Omg imgonnafailnfiedkla use complete sentences to explain how the mass of hydrogen is conserved during cellular respiration.