Question

when balanced, which equation would have the coefficient 3 in front of any of the reactants?
o zn + hcl → zncl₂ + h₂
o h₂so₄ + b(oh)₃ → b₂(so₄)₃ + h₂o
o fe + agno₃ → fe(no₃)₂ + ag
o c₂h₄o₂ + o₂ → co₂ +h₂o

Explanation:

Step1: Balance the first equation

$Zn + 2HCl
ightarrow ZnCl_{2}+H_{2}$; no coefficient of 3 for reactants.

Step2: Balance the second equation

$3H_{2}SO_{4}+2B(OH)_{3}
ightarrow B_{2}(SO_{4})_{3}+6H_{2}O$; coefficient of 3 for $H_{2}SO_{4}$ (a reactant).

Step3: Balance the third equation

$Fe + 2AgNO_{3}
ightarrow Fe(NO_{3})_{2}+2Ag$; no coefficient of 3 for reactants.

Step4: Balance the fourth equation

$C_{2}H_{4}O_{2}+2O_{2}
ightarrow 2CO_{2}+2H_{2}O$; no coefficient of 3 for reactants.

Answer:

$H_{2}SO_{4}+B(OH)_{3}
ightarrow B_{2}(SO_{4})_{3}+H_{2}O$