Answer:
When monopolistically competitive firms advertise, in the long run they will still earn zero economic profit.
Step-by-step explanation:
Monopolistic competition happens when many producers sell products that are differentiated from one another and hence are not perfect substitutes
Based on this, the demand curve of a firm in a monopolistic competitive market will shift so that it is tangent to the firm's average total cost curve and this will make it impossible for the firm to make economic profit. The best that can be expected is to be able to break even
This means in the long run, a monopolistically competitive firm will make zero economic profit.
A good example is Hotel which can only raise its prices without losing all of its customers based on brand loyalty and distinct quality differentiation.