What is the sum of the coefficients when the following equation is balanced using whole numbers?

___ ${\text{F}}{{\text{e}}_2}{{\text{O}}_3}{\text{(s)}} +$ ___ ${\text{CO(g)}} \to$ ___ ${\text{Fe(s)}} +$ ___ ${\text{C}}{{\text{O}}_2}{\text{(g)}}$

A.     5

B.     6

C.     8

D.     9

D

One respondent stated that the equation was a difficult choice to test the balancing of chemical equations. However, this type of question has been asked several times on previous papers and 59% of candidates got the correct answer, D. Candidates should be exposed to the balancing of some challenging equations as part of the teaching programme.