A reaction was found to be second-order with respect to the concentration of carbon monoxide. If the concentration of carbon monoxide is doubled, with everything else kept the same, the rate of reaction will

Increase by a factor of 4

The correct answer is option 3. Increase by a factor of 4

If a reaction is second-order with respect to the concentration of carbon monoxide (CO), it means that the rate of the reaction is proportional to the square of the concentration of CO.

When the concentration of CO is doubled while everything else is kept the same, the rate of the reaction will increase by a factor related to the change in concentration. Let's examine the effect of doubling the concentration:

Original rate: \(k[CO]^2\)

Doubled concentration: \(2[CO]\)

New rate: \(k(2[CO])^2 = 4k[CO]^2\)

Comparing the new rate (\(4k[CO]^2\)) to the original rate (\(k[CO]^2\)), we can see that the new rate is four times the original rate. Therefore, the correct answer is \((3)\) Increase by a factor of 4.