Chapter No 14 Chemistry Class 10 Notes

Chemistry Class 10 Notes CHAPTER NO.14
ENVIRONMENTAL CHEMISTRY I: Atmosphere

Q.1: Describe the layers of the environment.

Ans: Environment consists of four layers which are:

i. Lithosphere or Geosphere ii. Hydrosphere

iii. Biosphere iv. Atmosphere

i. Lithosphere:

The lithosphere consists of the rocky crust of the earth, soil minerals, and organic matter.

ii. Hydrosphere:

Hydrosphere consists of all water bodies like oceans, lakes, rivers, streams, springs, glaciers, and underground water.

iii. Biosphere:

The biosphere is the region of the earth that is capable to support life. The biosphere consists of plants animals and all the things to support them.

iv. Atmosphere:

The layers of gases surrounding the earth are called the atmosphere. It contains gases like oxygen, nitrogen, carbon dioxide, and noble gases.

Q.2: What is environmental chemistry?

Ans: Environmental chemistry (or) Ecology;

"The branch of chemistry which deals with the study of the environment and the changes occurring in it is called environmental chemistry." OR "The branch of chemistry which deals with the study of interactions of chemical substances/processes with the environment and their effects on it are called environmental chemistry."

Air pollution and water pollution are the two main areas studied in this branch of chemistry.

Q.3: Define the Atmosphere? Explain the composition and layers of the atmosphere.

Ans: Atmosphere:

"A thick protective blanket of air/gases around the earth which helps to sustain life is called the atmosphere."

1. Composition of atmosphere:

The composition of the atmosphere is given below:

i. Major constituents:

The major constituents of the atmosphere are nitrogen (78.1% by volume) and oxygen (20.9% by volume)

ii. Minor constituents:

The minor constituents of the atmosphere are:

i. carbon dioxide about 0.03%

ii. noble gases(about 1%) i.e. helium, neon, argon, krypton, xenon)

iii. Varying amount of water vapors and some other gases like methane, carbon monoxide, etc.

iii. Mass:

The mass of the atmosphere is about 4.5 to 5 x10¹⁵ metric tones.

iv. Density:

The density of the atmosphere is 0.0013g/cm³, which gradually decreases with altitude.

v.Temperature and pressure:

The temperature and pressure of the atmosphere change with the increase in altitude. The temperature ranges from -92 ^°C to 1200 ^°C. The pressure of the atmosphere at sea level is late but at high altitude, about 100Km, above sea level it decreases to 3x10-7atm.