2 Fe2O3 (s) → 4 Fe (s) + 3 O2 (s) ∆H = -97.0 kJ/mol Fe2O3, determine the mass of iron produced if the reaction yields 254 kJ of heat energy.

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

each  column  of the  table  is called a group. elements in a group share similar properties. groups are  read  from  top  to  bottom. metal. metalloid. nonmetal. solid. liquid. gas. fe. hg. o.  2. 3. 4. 5. 6. 7. 8. 9.  2. beryllium. 9.012. 4.  sodium. 22.990.  11. 3.  magnesium. 24.305.  12.  potassium. 39.098.  19. 4.  calcium. 40.078.  20. i guess  i