This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Here are the solutions to your questions: i) Name a substance which is responsible for the depletion of the ozone layer and explain how this substance contributes to the depletion of the ozone layer. The substance responsible for the depletion of the ozone layer is Chlorofluorocarbons (CFCs). When CFCs are released into the atmosphere, they rise to the stratosphere. In the stratosphere, ultraviolet (UV) radiation from the sun breaks down CFC molecules, releasing chlorine atoms. These highly reactive chlorine atoms then act as catalysts, reacting with and breaking down ozone (O₃) molecules into oxygen (O₂), thereby depleting the ozone layer. ii) State two effects of the depletion of the ozone layer on life on earth. 1. Increased incidence of skin cancer and cataracts: The depletion of the ozone layer leads to more harmful UV-B radiation reaching the Earth's surface, which can cause DNA damage in humans, leading to higher rates of skin cancer and eye cataracts. 2. Damage to ecosystems: Increased UV radiation can harm phytoplankton, which form the base of marine food webs, disrupting aquatic ecosystems. It can also reduce crop yields and damage plant life on land. iii) Give two reasons why Cameroon relies more on hydroelectricity power plants for the supply of electricity instead of fossil fuels. 1. Abundant water resources: Cameroon has numerous rivers and a significant amount of rainfall, providing a natural and consistent source of water for hydroelectric power generation. This makes hydropower a readily available and cost-effective option. 2. Environmental benefits: Hydroelectricity is a renewable and clean energy source that produces minimal greenhouse gas emissions compared to fossil fuels. Relying on hydropower helps Cameroon reduce its carbon footprint and mitigate climate change. iv) Give one example of a green source of energy. One example of a green source of energy is solar energy. --- OPTION 2: COMMUNICATION Figure 11 shows a light signal entering into an optical fiber. The diagram illustrates the principle of Total Internal Reflection (TIR), which is how light signals travel through an optical fiber. The optical fiber consists of a central core (made of glass or plastic with a higher refractive index) and an outer cladding* (made of glass or plastic with a lower refractive index). When a light signal enters the core, it travels along the fiber. If the light ray strikes the boundary between the core and the cladding at an angle greater than the critical angle, it undergoes total internal reflection*. This continuous reflection of light within the core, without escaping into the cladding, allows the light signal to travel long distances with very little loss of intensity, enabling efficient data transmission.