Anhydrous lithium perchlorate (4.78g) was dissolved in water and re-crystallized. care was taken to isolate all the lithium perchlorate as its hydrate. The mass of the hydrated salt obtained was 7.21g . What hydrate is it

Iknow #2 is d. i just need to know why

What does a particular point on a line of a phase diagram represent? o a. the maximum temperature a substance can exist at without bonds breaking b. the pressure created by the kinetic energy of molecules at a particular temperature c. the melting point or boiling point of a substance at a specific pressure d. the conditions in which temperature and pressure have equal effects on a substance

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.