Is the reaction endothermic or exothermic?

4Al(s)+ 3O2(g)--> 2Al2O3(s)+ 3351 KJ

For which one of the following reactions is the value of δh° rxn equal to δh° f for the product? a. 2 h2 (g) + o2 (g) → 2 h2o (l) b. n2 (g) + o2 (g) → 2 no (g) c. 2 h2 (g) + o2 (g) → 2 h2o (g) d. h2o (l) + 1/2 o2 (g) → h2o2 (l) e. none of the above

Which of the following pairs of elements belong to the same groupa. h and he b. li and bec. c and pb d. ga and ge

What does a complete balanced chemical equation include? a. exothermic coefficients b. endothermic coefficients c. valence electrons d. molar coefficients