Examine the equation of a reversible reaction.

2SO2 + O2 ⇌ 2SO3

Which of the answer choices correctly lists the reverse reaction?

2SO2 + 2SO3 → O2

2SO3 + 2SO2 → O2

2SO3 + O2 → 2SO2

2SO2 + O2 → 2SO3

The correct answer for the reverse reaction is the third option starting from top.

Explanation:

If we examine the given chemical equation:

2SO2 + O2 ⇌ 2SO3

The double arrow indicates that the reaction goes in both directions:

2SO2 + O2 - > 2SO3

2SO3 - > 2SO2 + O2

However, the closest option for the real situation would be the product from the semirreaction reacting in turn with oxygen:

2SO3 + O2 - > 2SO2

Thus, the correct answer is the third.

2SO3 - > 2SO2 + O2 (not shown in the options)

Explanation:

In a reversible reaction, reactants react to produce products and products react to produce reactants, simultaneously.

Given the reversible reaction:

2SO2 + O2 ⇌ 2SO3

It has a forward reaction:

2SO2 + O2 - > 2SO3

and a reverse reaction:

2SO2 + O2 < - 2SO3