Final answer:
The water contained in the piston-cylinder assembly initially at 1.5 bar will undergo compression.
Step-by-step explanation:
The water contained in a piston-cylinder assembly initially at 1.5 bar will go through a process of compression. Compression is the reduction in volume and increase in pressure of a gas. In this case, the water will experience an increase in pressure due to the reduction in volume of the piston-cylinder assembly.