‎ 1. (a) (i) Three ways of conserving energy in the home: 1. Switching off lights and appliances when not in use 2. Using energy-efficient appliances (e.g., LED bulbs) 3. Using natural light and ventilation (ii) Calculate the energy used: Energy = Power × Time = 4000 W × 12 h = 4000 × 3600 × 12 (convert hours to seconds) = 4000 × 43200 = 172,800,000 J or 172.8 MJ --- 2. (b) (i) Two examples of acid-base indicators: 1. Litmus 2. Methyl orange (ii) Colour change in orange juice (acidic): - Litmus: Blue → Red - Methyl orange: Orange → Red --- 3. (c) (i) Four activities to ensure a green economy in Ghana:* 1. Recycling and waste management 2. Promoting renewable energy use 3. Practicing sustainable farming 4. Environmental education and awareness (ii) Two primary greenhouse gases: 1. Carbon dioxide (CO₂) 2. Methane (CH₄) --- 5. (a) Farming Systems: (i) Organic farming – This method avoids synthetic fertilizers and pesticides, using natural compost and biological pest control. (ii) Mixed farming – Farmers grow crops and raise livestock on the same land, creating a sustainable balance between plant cultivation and animal rearing. (iii) Mixed cropping – Different crops are planted together to optimize space, reduce pests, and improve soil health. ### 5. (b) Mixtures of Substances: (i) Oil and water – Heterogeneous mixture (the substances do not mix uniformly). (ii) Salt and water – Homogeneous mixture (salt dissolves completely, forming a solution). (iii) Ethanol and water – Homogeneous mixture (ethanol mixes uniformly with water). ### 5. (c) Renewable Energy & Heat vs. Temperature: (i) Why is solar energy renewable? - The sun continuously produces energy without being depleted. - It is naturally replenished and available indefinitely. (ii) Differences between heat and temperature: - Heat is the total energy of molecular motion; temperature measures its intensity. - Heat depends on mass; temperature does not. - Heat is measured in joules; temperature is measured in degrees (Celsius/Kelvin). ### 5. (d) Effects on the Nitrogen Cycle: (i) Leaching – Removes essential nitrogen compounds from soil, reducing fertility. (ii) Removal of leguminous plants – Reduces nitrogen fixation, limiting nitrogen availability in the soil. Follow the WAEC channel on WhatsApp: https://whatsapp.com/channel/0029Vak4Npc8qIzxoRRa1C1d