Question

When balanced, which equation would have the coefficient 3 in front of any of the reactants?
*
Zn + HCl ZnCl2 + H2
H2SO4 + B(OH)3 B2(SO4)3 + H2O
Fe + AgNO3 Fe(NO3)2 + Ag
C2H4O2 + O2 CO2 +H2O

Answer 1

H2SO4 + B(OH)3 → B2(SO4)3 + H2O

Balanced: 3 H2SO4 + 2 B(OH)3 → 1 B2(SO4)3 + 6 H2O

So the coefficient 3 appears in front of the reactant H2SO4.