Above a pressure of 200 atmospheres and at a temperature of 100 degrees celsius, water is in gas phase.
true or false?

The given statement is false.

Explanation:

When water is boiled at a pressure of 1 atm and temperature is 100 degree celsius then both liquid and vapor state of water exists in equilibrium.

But as the temperature reaches at more than 100 degree celsius then liquid state of water changes into vapor state.

But when above pressure of 200 atmospheres and at a temperature of 100 degrees Celsius water is heated then it will exist in liquid phase and not in vapor phase.

Therefore, we can conclude that the statement, above a pressure of 200 atmospheres and at a temperature of 100 degrees Celsius, water is in gas phase, is false.