A gas 'X' which is a deadly poison is found at the higher levels of atmosphere and performs an essential func…

Question

A gas 'X' which is a deadly poison is found at the higher levels of atmosphere and performs an essential function. Name the gas and write the function performed by this gas in the atmosphere. Which chemical is linked to the decrease in the level of this gas? What measures have been taken by an international organization to check the depletion of the layer containing this gas?

Accepted Answer

## Model Answer **Gas X — Ozone (O₃)** **Function:** Ozone at higher levels of the atmosphere shields the Earth's surface from harmful ultraviolet (UV) radiation from the Sun. UV radiation can cause skin cancer in human beings. **Chemical linked to depletion:** Chlorofluorocarbons (CFCs), used in refrigerants and fire extinguishers, are responsible for the decrease in ozone levels. **Measures taken:** In 1987, the United Nations Environment Programme (UNEP) forged an agreement to freeze CFC production at 1986 levels. It is now mandatory for all manufacturing companies to produce CFC-free refrigerators worldwide. *Source: Chapter 13, Section 13.2.1* --- ## Explanation This question covers four distinct points — name, function, chemical, and measures — so award yourself 1 mark per point roughly. Examiners expect **ozone** named clearly, **UV radiation/skin cancer** as the function, **CFCs** as the chemical, and the **UNEP 1987 agreement + CFC-free refrigerators** as measures. Do not lea…

Science — CBSE Class 10 board question