Which of the following is an unbalanced equation? CS_(2)+underline (2)O_(2)-gt CO_(2)+underline (2)SO_(2) underline (2)Na+underline (2)H_(2)O-gt underline (2)NaOH+H_(2) PbO_(2)+underline (2)H_(2)-gt underline (2)Pb+H_(2)O CaCO_(3)... CaO+CO_(2)

The correct answer is: Explanation: An unbalanced chemical equation is one in which the number of atoms of each element is not the same on both sides of the equation. In the given options, the equation is unbalanced because the number of atoms of each element is not the same on both sides.