Question

select the correct answer. which equation obeys the law of conservation of mass? a. 2fe + 3o₂ → 2fe₂o₃ b. 4fe + o₂ → 2fe₂o₃ c. fe + o₂ → fe₂o₂ d. 4fe + 3o₂ → 2fe₂o₃

Explanation:

Step1: Count Fe atoms

For option D:
Left - hand side: \(4\) Fe atoms.
Right - hand side: \(2\times2 = 4\) Fe atoms.

Step2: Count O atoms

Left - hand side: \(3\times2=6\) O atoms.
Right - hand side: \(2\times3 = 6\) O atoms.

Since the number of Fe and O atoms is the same on both sides of the equation \(4\text{Fe} + 3\text{O}_2 \to 2\text{Fe}_2\text{O}_3\), it obeys the law of conservation of mass.

For option A:
Left - hand side: \(2\) Fe atoms. Right - hand side: \(2\times2 = 4\) Fe atoms. Not balanced.
For option B:
Left - hand side: \(2\) O atoms. Right - hand side: \(2\times3 = 6\) O atoms. Not balanced.
For option C:
Left - hand side: \(1\) Fe atom. Right - hand side: \(2\) Fe atoms. Not balanced.

Answer:

D. \(4\text{Fe} + 3\text{O}_2 \to 2\text{Fe}_2\text{O}_3\)