Which of the following reaction is balanced? (a) AsO MnO AsO MnO 2H O → (b) MnO C O Mn CO → (c) 3 2 Cu 4HNO Cu(NO ) 2NO 2H O → (d) H S HNO H O NO S → Ans (c) Sol. In option (a), 2- - 3- AsO +MnO AsO +MnO +2H O → The number of hydrogen atom is 0 in reactant side and 4 on the product side. So, it is not balanced. In option (b), - 2- 2+ MnO +C O Mn +CO → The number of oxygen atom is 8 in reactant side and 2 on the product side. So, it is not balanced. In option (d), H S+HNO H O+NO+S → The number of oxygen and hydrogen atom is 3 and 3 respectively in reactant side and 2 and 2 respectively on the product side. So, it is not balanced. In option (c), 3 2 Cu+4HNO Cu(NO ) +2NO +2H O → Here, each atom is equal in number on both sides. Hence, it is balanced. Thus, the correct option is (c) 3 2 Cu+4HNO Cu(NO ) +2NO +2H O →