I have a variable that holds an expression. e.g: (> 1 2), how do i evaluate it?

Question

So I wrote this code. How do i get the x in the if statement to evaluate? at the moment, x always succeeds, and the if statement never fails.

(define expand
  (lambda (exp)
    (cond
     ((symbol? exp) exp)
     ((pair? exp)
      (case (car exp)
       ((and)
        (if (null? (cdr exp)) '(quote #t)
            (if (null? (cddr exp)) (cadr exp)
                (let ((x (cadr exp))
                      (thunk (lambda () (expand '(and ,(cddr exp))))))
                  (if x (thunk) 
                      `(quote ,x))))))
       (else exp)))
     (else exp))))

Answer 1

Use eval, for example:

(if (eval x (null-environment 5))
    (thunk)
    `(quote ,x))