which equation is balanced?\n○ 4h₂ + o₂ → h₂o + o\n○ h₂ + o₂ → h₂o + o₂\n○ 2h₂ + o₂ → 2h₂o\n○ h₂ + o₂ → h₂o

Explanation:

Step1: Check hydrogen atoms in first option

In $4H_2 + O_2\rightarrow H_2O+O$, left - hand side has 8 H atoms, right - hand side has 2 H atoms. Not balanced.

Step2: Check oxygen atoms in second option

In $H_2 + O_2\rightarrow H_2O+O_2$, left - hand side has 2 O atoms, right - hand side has 3 O atoms. Not balanced.

Step3: Check hydrogen and oxygen atoms in third option

In $2H_2 + O_2\rightarrow 2H_2O$, left - hand side has 4 H atoms and 2 O atoms. Right - hand side has 4 H atoms and 2 O atoms. Balanced.

Step4: Check hydrogen and oxygen atoms in fourth option

In $H_2 + O_2\rightarrow H_2O$, left - hand side has 2 O atoms, right - hand side has 1 O atom. Not balanced.

Answer:

$2H_2 + O_2\rightarrow 2H_2O$