An open flask is half filled with water at 25°c.
phase equilibrium can be reached after
(1) more water is added to the flask
(2) the flask is stoppered
(3) the temperature is decreased to 15°c
(4) the temperature is increased to 35°c

An open flask is half filled with water at 25 degrees Celsius. Phase equilibrium can be reached after the flask is stoppered. Equilibrium is defined as a state of balance or a stable situation where opposing forces cancel each other out and where no changes are occurring. Thermodynamics is usually subdivided into a theory dealing with equilibrium and into one concerned with irreversible process. 

Ibelieve the answer is d

Heat is involved in chemical change in two ways; chemical changes either result in heat being added to or removed from an object, and chemical changes require a certain amount of heat before they can take place.