The air in an inflated balloon (defined as the system) is warmed over a toaster and absorbs 120 j of heat. as it expands, it does 78 kj of work.

what is the change in internal energy for the system?

Answer : The value of for the system is -77880 J

Explanation :

First law of thermodynamic : It states that the energy can not be created or destroyed, it can only change or transfer from one state to another state.

As per first law of thermodynamic,

where,

= internal energy  of the system

q = heat absorbed by the system

w = work done  by the system

As we are given that:

q = 120 J

w = -78 kJ = -78000 J      (1 kJ = 1000 J) (system work done by system)

Now put all the given values in the above expression, we get:

Therefore, the value of for the system is -77880 J

i think it's c. i'm not sure but i think so.