Question

balancing chemical equations
multiple-choice question
how many h₂ do we need on the reactant side of this equation for a balanced equation?
4
2
1

Explanation:

Step1: Identify unbalanced equation

$H_2 + O_2
ightarrow H_2O$

Step2: Balance oxygen atoms

Add coefficient 2 to $H_2O$:
$H_2 + O_2
ightarrow 2H_2O$

Step3: Balance hydrogen atoms

Add coefficient 2 to $H_2$:
$2H_2 + O_2
ightarrow 2H_2O$

Step4: Verify atom counts

Reactants: 4 H, 2 O; Products: 4 H, 2 O. Equation is balanced.

Answer:

2