What happens when CFC or HCFC molecules are released in the stratosphere?

• A. They create carbon dioxide
• B. They destroy ozone molecules and produce chlorine monoxide
• C. They synthesize new ozone molecules
• D. They transform into water vapor

Answer: (B)

When chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs) are released into the atmosphere, they eventually reach the stratosphere, where they undergo photodissociation due to UV radiation. This process breaks down the CFC or HCFC molecules, releasing chlorine atoms. These chlorine atoms are highly reactive and can interact with ozone (O3) molecules in the stratosphere.

The chlorine atoms catalyze the destruction of ozone by reacting with it and converting it into oxygen (O2) and chlorine monoxide (ClO). This reaction can occur repeatedly, meaning that a single chlorine atom can destroy thousands of ozone molecules before being deactivated. The production of chlorine monoxide is a significant concern because it signifies the ongoing depletion of the ozone layer, which protects life on Earth from harmful UV radiation.

Other choices do not accurately reflect the chemistry of CFCs and HCFCs in the stratosphere. For instance, the production of carbon dioxide or the transformation into water vapor does not occur with these substances in the context given. Additionally, there is no synthesis of new ozone molecules by these compounds; rather, they contribute to ozone depletion. Thus, the correct answer highlights the critical