Tag: science & technology

Trees provide essential human needs including oxygen, food, shelter, fuel, and materials. They help combat climate change by absorbing carbon dioxide and prevent soil erosion. Despite these benefits, deforestation continues due to human greed and short-term economic interests.

Greenhouse gases including carbon dioxide, methane, and nitrous oxide trap heat in Earth's atmosphere, causing global warming and climate change. The riddle's reference to 'warming up the climate' directly identifies these gases. They are 'more dangerous than we appear' because they are invisible yet have catastrophic global effects.

When you're the last person leaving a room, you should turn off the light to save energy. 'Turn off the light' is the correct environmental practice. Turning it on would waste energy, and doing nothing defeats the purpose.

Trees are cut down to make paper, causing deforestation. The blank should be 'Trees' - they are 'felled' (cut down) for paper production. Carbon and lead are not felled to make paper; only trees are directly relevant to paper manufacturing.

Plastic bags are environmental hazards - they cause litter, clog drains, choke landfills, and persist in the environment for centuries without degrading. The question advocates avoiding plastic bags for these reasons. Cloth and paper bags are eco-friendly alternatives.

Ultraviolet (UV) rays are used to detect counterfeit currency because many security features fluoresce or become visible only under UV light. These include security threads, watermarks, and invisible ink markings. Alpha and Beta rays are nuclear radiation, and ordinary light rays cannot reveal these hidden security features.

The sky appears blue due to Rayleigh scattering, where shorter blue wavelengths of sunlight are scattered more than longer red wavelengths by molecules and tiny particles in the atmosphere. This scattered blue light reaches our eyes from all directions. Refraction involves bending, and reflection involves bouncing - neither explains the sky's color.

A capacitor stores electrical energy in an electric field between two conductive plates. Resistors limit current flow, inductors store energy in magnetic fields, and conductors simply allow current to pass without storage.

Increased pressure inside a pressure cooker raises the boiling point of water above 100°C. At standard atmospheric pressure, water boils at 100°C, but higher pressure requires higher temperature for boiling.