Question

which balanced equation involves 12 atoms of oxygen?
a ( 5o_{2}
ightarrow 5o_{2} )
b ( 2c_{3}h_{8}+10o_{2}
ightarrow 6co_{2}+8h_{2}o )
c ( 4fe + 3o_{2}
ightarrow 2fe_{2}o_{3} )

Explanation:

Step1: Calculate oxygen atoms in option A

In \(5O_{2}\), oxygen atoms \(=5\times2 = 10\)

Step2: Calculate oxygen atoms in option B

In \(10O_{2}\), oxygen atoms \(=10\times2=20\); in \(6CO_{2}\), oxygen atoms \(=6\times2 = 12\); in \(8H_{2}O\), oxygen atoms \(=8\times1=8\). Total oxygen atoms \(=20 + 12+8=40\)

Step3: Calculate oxygen atoms in option C

In \(3O_{2}\), oxygen atoms \(=3\times2 = 6\); in \(2Fe_{2}O_{3}\), oxygen atoms \(=2\times3=6\). Total oxygen atoms \(=6 + 6=12\)

Answer:

C. \(4Fe + 3O_{2}\to2Fe_{2}O_{3}\)