Which statement concerning ozone is incorrect?

In this scenario, the statement about ozone residual lasting several hours is not accurate. Ozone has a relatively short half-life in water, usually decomposing within 20 to 30 minutes. This rapid breakdown means that ozone does not remain stable or provide a lingering residual effect in a manner similar to chlorine, which can persist for hours or even longer in treated water.

The other statements about ozone being a faster disinfectant than chlorine and being more expensive are correct. Ozone acts as a powerful oxidant and disinfectant, often working more quickly than chlorine to inactivate pathogens. Additionally, the production and application of ozone, especially due to the equipment requirements and the method of generation, typically leads to its higher costs compared to chlorine.

Therefore, the focus on ozone’s lack of a lasting residual effect reinforces why the first statement is the one that does not hold true, while the others accurately describe the characteristics and comparative performance of ozone in the context of disinfection.