fa-lightbulb Everyday Science

Explanation: Acid rain is caused by sulfur dioxide (SO2) and nitrogen oxides (NOx) from burning fossil fuels reacting with water in the atmosphere to form sulfuric and nitric acids.

Explanation: Carbon dioxide (CO2) produced by burning fossil fuels is the primary human-caused contributor to global warming. Though less potent than methane, it persists longer in the atmosphere.

Explanation: Biodiversity refers to the variety and variability of life on Earth, including diversity within species, between species and of ecosystems. High biodiversity indicates a healthy ecosystem.

Explanation: Chlorofluorocarbons (CFCs), once used in refrigerants and aerosols, are the main cause of ozone depletion. UV radiation breaks them down to release chlorine atoms that destroy ozone molecules.

Explanation: The greenhouse effect occurs when greenhouse gases (CO2, methane, water vapor etc.) in the atmosphere trap heat from the sun, warming the Earth's surface. Human activities have enhanced this effect.

Explanation: The stapes (stirrup bone) in the middle ear is the smallest bone in the human body, measuring about 3mm. It transmits sound vibrations from the eardrum to the inner ear.

Explanation: A normal resting heart rate for adults is 60-100 beats per minute. Athletes may have lower resting heart rates (40-60 bpm) due to greater cardiovascular efficiency.

Explanation: The average normal human body temperature is 37°C (98.6°F). A fever is generally defined as a temperature above 38°C (100.4°F).

Explanation: Vitamin D (the sunshine vitamin) is synthesized in the skin when ultraviolet B (UVB) rays from sunlight strike the skin. It is essential for calcium absorption and bone health.

Explanation: An adult human has 32 permanent teeth, including 4 wisdom teeth (third molars). Without wisdom teeth, the count is 28. Children have 20 primary (milk) teeth.