No.

All languages are typed in one way or another. Unless you write a generic function, you cannot evaluate (+ 2 "a") in scheme. Here is racket's error message:

    > (+ 2 "a")
    ; +: contract violation
    ;   expected: number?
    ;   given: "a"
    ;   argument position: 2nd
    ; [,bt for context]
    >

The function absolutely expects its arguments to have a certain shape (type). The difference with C is that variables don't have types set in stone, they can... vary. The compiler/interpreter just takes care of them for you.