6.
(i) Cluster 2 is more distant. Its MS is shifted to larger apparent magnitudes.
(ii) The MS of cluster 2 is approximately 5 magnitudes fainter. Since m-M=5log(d/10pc), it follows that it is 10x more distant than cluster 1.
(iii) In cluster 2, the MS turnoff occurs at higher B-V (i.e. redder colours). This means that lower mass stars have had time to evolve off the MS in cluster 2 - hence it must be older than cluster 1.