Using Scheme Language,

Another thing you have to master in learning Scheme and Lisp is how to access elements in an s-expression. In the following table, the first column lists some s-expressions containing a single instance of the atom X. Assume that the variable S is bound to the s-expression in the first column. The second column should be an expression that when evaluated returns the atom X. You are only allowed to use the functions car and cdr and a single instance of the variable s. We've done the first row for you as an example. You should, of course, verify your work using the Scheme interpreter. In doing so, you can assign s a value using the define function, e.g., do (define S '(x)) when checking your answer for 2.ex.

Expression to return the atom x 2.ex 2.a 2.b 2.c 2.d 2.e (car S) (1 2 (x))