Science — CBSE Class 10 board question

The ozone layer ($O_3$) present in the upper atmosphere shields the Earth's surface from harmful ultraviolet (UV) radiation from the Sun. Depletion of this layer is a cause of concern because:

1. UV radiation is highly damaging to living organisms — it causes skin cancer in human beings.
2. Synthetic chemicals like CFCs (chlorofluorocarbons), used in refrigerators and fire extinguishers, have caused a sharp drop in ozone levels since the 1980s.
3. Without the ozone shield, increased UV exposure can severely damage the entire environment and all life forms on Earth.

Source: Chapter 13, Section 13.2.1 — Ozone Layer and How it is Getting Depleted

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Examiners look for three clear points for 3 marks: (1) what ozone does (shields UV radiation), (2) what happens if it is depleted (skin cancer / damage to organisms), and (3) the cause (CFCs). Mentioning UNEP/1987 agreement is a bonus but not required. Avoid writing a long essay — keep it to 3 crisp points as shown.