Liquid nitrogen has different properties from gaseous nitrogen. is it a chemical change when liquid nitrogen warms to gaseous nitrogen?

Can someone me with these questions plz.

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.

Sulfuric acid is a polyprotic acid. write balanced chemical equations for the sequence of reactions that sulfuric acid can undergo when it's dissolved in water.