Question

1. which of the following is a balanced chemical equation describing the formation of water?

2h₂ + 2o₂ → 2h₂o
h₂ + 2o₂ → h₂o
h₂ + o₂ → h₂o
2h₂ + o₂ → 2h₂o

Explanation:

Step1: Count H, O for Option 1

Reactants: $2\text{H}_2 + 2\text{O}_2$ → H: $2\times2=4$, O: $2\times2=4$; Products: $2\text{H}_2\text{O}$ → H: $2\times2=4$, O: $2\times1=2$. O unbalanced.

Step2: Count H, O for Option 2

Reactants: $\text{H}_2 + 2\text{O}_2$ → H: 2, O: $2\times2=4$; Products: $\text{H}_2\text{O}$ → H:2, O:1. O unbalanced.

Step3: Count H, O for Option 3

Reactants: $\text{H}_2 + \text{O}_2$ → H:2, O:2; Products: $\text{H}_2\text{O}$ → H:2, O:1. O unbalanced.

Step4: Count H, O for Option 4

Reactants: $2\text{H}_2 + \text{O}_2$ → H: $2\times2=4$, O:2; Products: $2\text{H}_2\text{O}$ → H: $2\times2=4$, O: $2\times1=2$. All atoms balanced.

Answer:

$\boldsymbol{2H_2 + O_2
ightarrow 2H_2O}$ (the fourth option)