What are the three sets of marginal conditions necessary for the efficient allocation of resources? When will the 'free rider' problem occur? Is a state of perfect competition in all markets...

What are the three sets of marginal conditions necessary for the efficient allocation of resources? When will the 'free rider' problem occur?

Is a state of perfect competition in all markets necessary and sufficient to ensure a Pareto optimal allocation of resources? Assuming that a social welfare function can be imposed, is perfect competition boThnecessary and sufficient to achieve the allocation of resources that maximises social welfare.