Which of the following is impossible?
(a). Silver foil that is 1.2 × 10⁻⁴ m thick
(b). A sample of potassium that contains 1.784 × 10²⁴ atoms
(c). A gold coin of mass 1.23 × 10⁻³ kg
(d). 3.43 × 10⁻²⁷ mol of S8 molecules