Page 111 - ICSE Chemistry 6

Observa on: You will see bubbles of gas collec ng in the test tube.
Procedure
• Remove the test tube when it has been fi lled with gas. Remember to close its mouth with your
thumb.

• Next bring a glowing splinter near the mouth of the test tube containing gas.
Observa on: The splinter starts burning with a bright fl ame.

Conclusion: This confi rms that the gas produced is oxygen. Hence, oxygen is produced during the process
of photosynthesis.

Take a Break!

Write/Choose the correct answer.

1. In the process of respira on carbon dioxide is consumed. (True/False)
2. ____________ is widely used as a cooking fuel and to keep warm.

3. Chlorophyll is a (green-coloured/brown-coloured) pigment.
4. Respira on and photosynthesis are two opposing processes. (True/False)

AIR POLLUTION

Air is a mixture of gases that forms the atmosphere necessary for
sustenance of life. Any imbalance caused by the change in the
propor on of these gases can be harmful for survival.
Air pollu on arises due to release of harmful par cles and gases into
air that have damaging eff ects on living things and the environment.
Air pollutants are gases and par cles in the atmosphere that harm
organisms and aff ect climate. The main air pollutants are smoke,
dust, vapour, soot and gases like carbon dioxide, chlorofl uorocarbons
(CFCs), sulphur dioxide, nitrogen oxide, methane, ammonia, etc.
Fig. 5.5: Vehicles on a busy street
Causes of Air Pollution

• Burning of fossil fuels in places like coal-burning plants release a lot of harmful gases.
• Emissions from vehicles like cars, planes and boats contribute
to air pollu on.
• Use of insec cides, pes cides and fer lisers in agricultural
ac vi es release harmful chemicals into the air.
• Factories and industries release large number of harmful
chemicals into the air.
• Increased popula on has led to indiscriminate cu ng of forests
for residen al and agricultural purposes. This has resulted in
Fig. 5.6: Smoke from factories
air pollu on.

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