Explain why genes located more than 50 map units apart behave as if they are not linked. b. discuss how can one determine whether these genes are linked and what the relative distance is between them?

This is on account of every chromosome just has up to 50 units so when it surpassed this number it's on an alternate chromosome, along these lines it can't be connected. 
One can decide whether qualities are connected or not by taking a gander at the posterity and deciding the recombination recurrence you can do this by taking the aggregate number of posterity that were recombined and partitioning it by the aggregate

The answer is constant.