The ozone layer is found in the

Analyze the question: You are asked which layer of the atmosphere contains the ozone layer.

Explain the concept: The atmosphere is divided into layers based on temperature changes with height:

1. Troposphere (0 to about 12 km): the layer where we live. It contains most of the water vapour, clouds and weather.
2. Stratosphere (about 12 to 50 km): this layer contains the ozone layer. Ozone (O₃) absorbs harmful ultraviolet (UV) radiation from the sun, so temperature actually increases with height here.
3. Mesosphere (about 50 to 85 km): the coldest layer, where meteors burn up.
4. Thermosphere (above about 85 km): this contains the ionosphere, a region of charged particles (ions) that reflects radio waves.
5. Exosphere: the outermost layer, which gradually merges into space.

Solution, step by step:

• Exosphere (A): the outermost layer, with very thin air. It has no ozone layer.
• Ionosphere (B): this is a zone of ionized particles in the upper atmosphere. It is important for radio communication, not for ozone.
• Stratosphere (C): ozone is concentrated here, especially at about 15 to 35 km. This matches the question.
• Troposphere (D): there is some ozone here, but it is a pollutant at ground level. The protective ozone layer is not in this layer.

Answer: C. Stratosphere

Tip: Link the words: Stratosphere = Sunscreen. The ozone layer shields us from the sun's UV rays. Also remember that the troposphere is the "weather layer" and the ionosphere is the "radio layer."