1.)which is the correctly balanced equation? a. cl2 + nai à nacl + i2 b. 2cl2 + nai à 2nacl + i2 c. cl2 + 2nai à 2nacl + i2 d. cl2 + 2nai à nacl + 2i2 2. the following is an example of which type of reaction? ch3oh + o2 → co2 + 2h2o + heat a. combustion b. endothermic c. substitution d. spontaneous 3.which of the following equations is balanced? a. h2+ o2→h2o b. 2h2 + o2→2h2o c. 4h2 + o2→h2o + o d. h2 + o2→h2o + o2

A. The correctly balanced equation is that in which the number of atoms of a certain element at the left-hand side is similar to that in the right hand side or the reactant side and product side, respectively. From the given equation, the answer would be,

       C. Cl2 + 2NaI --> 2NaCl + I2

B. In the given chemical reaction above, heat is emitted such that it appears in the product side of the equation. Hence, this is an example of a combustion reaction. 

C. Similar with the reasoning in letter A, the answer to this item is,
          B. 2H2 + O2 --> 2H2O