Which of the following sources of energy contributes to green-house effect?

Step 1: Analyze the question The greenhouse effect is caused by gases like carbon dioxide (CO₂), methane (CH₄), and water vapour that trap heat in the atmosphere. We need to find the energy source that releases such gases when used.

Step 2: Explain the concept

• Fossil fuels (coal, crude oil, natural gas) release CO₂ when burned.
• Renewable and clean sources (wind, solar) produce no greenhouse gases while generating power.
• Nuclear energy produces no CO₂ during operation. Its concerns are radioactive waste, not the greenhouse effect.

Step 3: Work through the options

• A. Natural gas: It is mainly methane. Burning it gives CO₂ and water: CH₄ + 2O₂ → CO₂ + 2H₂O Methane itself is also a potent greenhouse gas if it leaks. So it contributes to the greenhouse effect.
• B. Nuclear: It generates energy by fission and releases no CO₂. It does not contribute.
• C. Wind: It uses moving air to turn turbines and produces no emissions. It does not contribute.
• D. Solar: It uses sunlight and produces no greenhouse gases during use. It does not contribute.

Step 4: Answer The correct option is A. Natural gas.

Exam tip: For "greenhouse effect" questions, look for the carbon-based fuel (coal, petrol, diesel, natural gas, wood). If the energy source burns and contains carbon, it releases CO₂. If it does not burn (wind, solar, hydro), it is clean.