At a pressure of 200atm, water's melting point is approximately what and its boiling point is approximately what?

Answer 1

here's a phase diagram for H2O https://upload.wikimedia.org/wikipedia/commons/3/3...

note that 200 atm = 200atm * (101.325 kPa / 1 atm) * (1 MPa / 1000kPa) = 20MPa

and if you don't understand "critical point"

https://en.wikipedia.org/wiki/Critical_point_(ther... 

Answer 2

There's little Chemistry in this question.  You might get more answers by moving it to Physics.