Please use Scheme to code

Given two lists A and B, write a function to compute the difference A B, where A B is the list of elements that are in A but not in B. For example, if A is (6 7 8 9) and B is (7 9) then A B is (6 8).

Given a list of numbers, write a function to perform the square operation for each member of the list and return a list of squares. For example, (square (1 2 3 4)) would give (1 4 9 16).