What is the correct balanced equation for the following equilibrium constant expression? co2 (g) two arrows stacked on top of each other. the top arrow points to the right. the bottom arrow points to the left. co (g) + ½ o2 (g) co2 (g) two arrows stacked on top of each other. the top arrow points to the right. the bottom arrow points to the left. co (g) + o2 (g) 2 co2 (g) two arrows stacked on top of each other. the top arrow points to the right. the bottom arrow points to the left. 2 co (g) + o2 (g) 2co (g) + o2 (g) two arrows stacked on top of each other. the top arrow points to the right. the bottom arrow points to the left. co2 (g)

The correct answer is 3) 2CO2(g) ⇄ 2CO(g)  + O2(g)

this is the correct one because it is a decomposition reaction and all the number of atoms is equal on both sides.

there are 2 C atoms on both sides. 

and 4 O atoms on both sides.

and 1) the atoms numbers are equal on both sides but not correct as it not a

correct number as it has 1/2 O2.

and 2) CO2(g) ⇆ CO(g) + O2 

the number of O atoms is not equal on both sides of the equation.

we have 2 O atoms on the left side and 3 O atoms on the right side.

so, this not a balanced equation.

4) also not correct 2CO(g) + O2 ⇆ 2CO2

as it is not a decomposition reaction and the 2CO & O2 are as reactants not products.

so the correct answer is 3) 2CO2(g) ⇆ 2CO(g) + O2(g)