Is B2O3 molecular or ionic

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

Which statement best describes the oxidation numbers of the atoms found in magnesium chloride? a. magnesium has a 2- oxidation number and chlorine has a 1+ oxidation number. b. magnesium has a 2- oxidation number and chlorine has a 2+ oxidation number. c. magnesium has a 2+ oxidation number and chlorine has a 1- oxidation number. d. magnesium has a 1+ oxidation number and chlorine has a 1- oxidation number.

Explain which group an element with the electron configuration 1s2 2s2 2p6 3s2 3p6 3d1 4s2 belongs to.