its urgent

Q.1. It is an assumption of perfect competition that, in the long run, no firm makes supernormal profits, only normal profit. Does that mean that all firms in perfect competition make the same level of profit? Q.2 "Costs play a key role in determining theoretically the optimum level of production". Explain the statement. Q.3 Show that normal goods have a positive value of income elasticity of demand and inferior goods have a negative value of income elasticity of demand