Question

the decomposition of water into hydrogen gas h₂ and oxygen gas o₂ can be modeled by the balanced chemical equation
a h₂ + o₂ → h₂o
b h₂o → h₂ + o₂
c 2h₂ + o₂ → 2h₂o
d 2h₂o → 2h₂ + o₂

Explanation:

Step1: Understand decomposition reaction

Decomposition of water means water breaks down into hydrogen and oxygen. Water is the reactant and hydrogen and oxygen are products.

Step2: Check atom - balance

In a balanced chemical equation, the number of atoms of each element on the reactant side is equal to that on the product side. For the decomposition of water ($H_2O$) into hydrogen ($H_2$) and oxygen ($O_2$), the balanced equation is $2H_2O
ightarrow 2H_2 + O_2$. In option A, the equation is not balanced for oxygen. In option B, the equation is not balanced for oxygen. In option C, it represents the formation of water, not its decomposition.

Answer:

D. $2H_2O
ightarrow 2H_2 + O_2$