Refer to figure.
The purpose of the turbine is to extract as much energy as possible from the air exiting the gas chamber. This is achieved with the guide vanes and blades, by harvesting energy from the expanding hot air and therefore the kinetic energy of the airflow. Meaning the turbine will use the high pressure from the hot air exiting the combustion chamber and convert that into useful energy.

In the figure it can easily be seen that the pressure decreases along the turbine section of the graph.

Incorrect answers:

• “Axial velocity decreases”: Even though the main purpose of the turbine is to extract energy from the air entering the combustion chamber, the airflow is actually faster in the turbine section than it is in the combustion chamber. Along the turbine, the axial velocity fluctuates up and down as it passes through each guide vane and turbine blade.
• “Temperature increases”: As the turbine extracts energy from the air, the temperature decreases axially the further it gets from the combustion chamber.