100 points free and brainliest, cuz i dont care anymore

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

Achemistry student weighs out 0.306 g of citric acid (h3c6h5o7), a triprotic acid, into a 250 ml volumetric flask and dilutes to the mark with distilled water. he plans to titrate the acid with 0.1000 m naoh solution. calculate the volume of naoh solution the student will need to add to reach the final equivalence point. be sure your answer has the correct number of significant digits.

Ineed ! i have no clue how to do this problem.