The gas that is most useful in protecting humans against solar marathon is

Analyze the question: The question appears to have a typo. "Solar marathon" most likely means "solar radiation," specifically the harmful ultraviolet (UV) rays from the sun. So it is asking which gas protects humans from harmful solar radiation.

Concept: The Earth's stratosphere contains the ozone layer. Ozone (O₃) absorbs most of the sun's harmful ultraviolet radiation (UV-B and UV-C) before it reaches the Earth's surface.

Solution, option by option:

• A. Chlorine: A toxic gas used to disinfect water. It does not shield us from the sun. Chlorine-containing compounds (CFCs) actually destroy the ozone layer.
• B. Ozone: It forms a protective layer in the upper atmosphere that absorbs UV radiation. Without it, we would face a higher risk of skin cancer, cataracts, and damage to crops.
• C. Carbon IV oxide: It is a greenhouse gas that traps heat. It is not a UV shield.
• D. Hydrogen sulphide: A poisonous gas that smells like rotten eggs. It has no protective role against solar radiation.

Answer: The ozone layer protects us, so the correct option is B.

Exam tip: Remember "Ozone = Our shield (against UV)." Also link these together: CFCs → destroy ozone → more UV reaches Earth. JAMB often tests this link, as well as the greenhouse gases (CO₂, CH₄) that cause global warming, so don't mix the two up.