The level of water in a measuring cylinder rose to 90cm³ mark when a piece of stone whose mass is 10 g was dropped in the measuring cylinder. the initial volume of the water as 50 cm³ calculate the density of the rock. show working ( means show your calculations of how you solved it :] ) pleaae this is under science but it's not giving me that option so i choose chemistry

Achemistry student needs to standardize a fresh solution of sodium hydroxide. he carefully weighs out of oxalic acid , a diprotic acid that can be purchased inexpensively in high purity, and dissolves it in of distilled water. the student then titrates the oxalic acid solution with his sodium hydroxide solution. when the titration reaches the equivalence point, the student finds he has used of sodium hydroxide solution.calculate the molarity of the student's sodium hydroxide solution. be sure your answer has the correct number of significant digits.