Quiz on International Day for the Preservation of the Ozone Layer

Here is a quiz to help deepen the understanding of why it is important to preserve the ozone layer.

1 / 7

Q. 1 What is the molecular formula of ozone?

Answer Detail:

Ozone (O3) is a triatomic molecule, consisting of three oxygen atoms. Ozone protects living organisms by preventing damage from ultraviolet light reaching the Earth's surface. O3 is the formula for ozone. It has three oxygen atoms.


Q. 2 Why is the ozone layer important?

Answer Detail:

The ozone layer is important as it protects the Earth against most Ultraviolet B (UVB) rays coming from the sun, which are very harmful for the body. Ultraviolet B (UVB) rays can cause various diseases as well as mutation of cells. It is always important to protect oneself against UVB, even in the absence of ozone depletion, by wearing hats, sunglasses, and sunscreen. However, these precautions will become more important as ozone depletion worsens.


Q. 3 What is the main cause of ozone layer depletion?

Answer Detail: The 2 main gases responsible for the depletion of the ozone layer are chlorofluorocarbons (CFCs) and halogen-source gases in the stratosphere which are widely used in industrial and consumer applications. An example of a refrigerant CFC is dichlorodifluoromethane, CF2Cl2 (also known as CFC-12), which boils at -30°C. Another once-common CFC is trichlorofluoromethane, CFCl3 (CFC-11), which boils at 24°C and was once the propellant in around half of all the aerosol cans used in the world. 
The halogen source gases, often referred to as ozone-depleting substances (ODSs), include manufactured chemicals released to the atmosphere in a variety of applications, such as refrigeration, air conditioning, and foam blowing.

Q. 4 Where is the ozone hole located?

Answer Detail: The ozone hole is not technically a “hole” where no ozone is present, but is actually a region of exceptionally depleted ozone in the stratosphere over Antarctica that happens at the beginning of Southern Hemisphere spring (August–October). The depletion of ozone layer is caused by CFCs which are released because of various human activities. These CFCs can stay in the lower atmosphere for years or even decades, and eventually reach the stratosphere. The ultraviolet rays, which are released from the sun, breaks down these CFCs into cholrine atoms. A free chlorine atom then undergoes many chemical reactions which destroys the ozone layer. In addition to these existing chlorine atoms, other free chlorine atoms continue to be formed and are released into the atmosphere, which repeats the cycle of ozone depletion. 

Q. 5 Which Sustainable Development Goals (SDG) does the goal preservation of the ozone layer come under?

Answer Detail:  According to the United Nations 17 SDGs, the goal of ensuring “preservation of the ozone layer” comes under SDG 13.

Q. 6 Which year is the ozone layer expected to return to its normal level if all precautions are taken?

Answer Detail:

The ozone layer is expected to return to normal levels by about 2050, but it is very important that the world comply with the Montreal Protocol; delays in ending production and use of ozone-depleting substances could cause additional damage to the ozone layer and prolong its recovery.


Q. 7 Which international treaty is designed to protect the ozone layer?

Answer Detail: The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 September 1987 and entered into force on 1 January 1989.