If a gas expands, is the work done positive, negative, or zero?

The first law of thermodynamics then reduces to

dQ = dW + dU ⇒ dU = −dW (1)

where dW is the amount of work done by the gas and dU is the change in internal energy.

Since the gas is expanding, the work being done by the gas is positive. Eqn. (1) then implies that the change in internal energy of the system must be negative, that is, the internal energy

is decreasing. The only true statements are then:

• The work done by the gas is positive, and no heat exchange occurs.

• The internal energy of the system decreases.

this is an outline for the decisions that frankie is going to make

opportunity cost

willingness to buy

price or quality

of course, there could be many economic strategies that should be considered important while making decision. opportunity cost is the foremost significant factor while considering any economic option. when you buy something, you should know how much you are forgoing for this product. indeed, you could buy something different with this measure if you changed your mind. willingness to buy shows how much surplus you are earning while making a decision. it is important because it shows you buy what you want or you buy because you have only limited amount of money. the price or quality can be considered as a general economic option that we are applying while buying something. when you buy something, price or quality could be one of the options. indeed, they define the characteristics of the product.    

mark brainliest!

answer; i believe the correct answer is (general);