Question

Draw a first-law bar chart (see Figure 19.12) for the gas process in Figure EX19.6.

Short answer

The work is positive level and heat is negative level.

Step-by-step solution

Definition of isobaric  process 

Isobaric process defines that the pressure remain constant due to change of variables.

Finding the major points of the diagram.

Based of the graph, the volume decrease that means $V_f>V_i$and work done is positive due to the energy goes from environment to system.

As per isolate gas equation if volume decrease then temperature also decrease. Due to this reason internal energy and heat decrease and work done is increased. So $E_{thi}>E_{thf}$