The science or the field of study concerned with the study of solid Earth, soil, the air surrounding it, its atmosphere, its gravitational force and its waters, including the geologic, hydrologic cycles, is known as Earth science. Earth science is an amalgamation of many sciences and theories related to the planet Earth.
Studying and analysing the past evolution of Earth, understanding the present features and determining the future consequences of its present condition is the broader aim of studying Earth science. And later, using this knowledge for the benefit of humankind is the ultimate goal to save future generations and the planet. Thus, observing, describing, and categorising all the geographies of Earth is the basic concern of the Earth scientist.
In simpler words, the definition of Earth science can be concluded as the branch of science dealing with the atmosphere of Earth and its physical elements.
Groups of Earth Science
There are basically six assemblies of Earth science topics, and they are:
- The first one consists of disciplines that examine air and water above or on the surface of Earth.
- The second one involves the studies about the formation of the solid Earth.
- The third group consists of a detailed study of landforms.
- The fourth one inspects Earth’s history.
- The fifth group contains Earth science’s helpful, practical applications related to energy, its use and guarding Earth against natural hazards.
- The sixth group studies celestial bodies’ rock records and is made up of astrogeology and analogous disciplines.
Important Questions on Earth Science
1) Without changing the radius if the density of the planet is doubled, then what effect will it have on the ‘g’ of the planet?
a) It will remain the same
b) ‘g’ will be tripled
c) ‘g’ will reduce to half
d) ‘g’ will be doubled
Correct Option: (d)
Explanation: ‘g’ is proportional to the density of the planet; therefore, without changing the radius, if the density of the planet is doubled, then g also gets doubled.
2) As compared to the force of gravity of the moon on the Earth, what will be the force of gravity of the Earth on the moon, if the moon’s mass is approximately 10% of the mass of the Earth?
a) Both the forces will be equal
b) There will be no change
c) The force of gravity of the moon on the Earth is much lesser
d) None of these
Correct Option: (a)
Explanation: Since the mass of the moon is 10% of the mass of the Earth and the gravitational force between the two bodies is a mutual force, the force of gravity of the Earth on the moon will be equivalent as compared to the gravitational force of the moon on Earth.
3) The value of the dip angle at the magnetic North Pole of the Earth will be ______.
a) Maximum
b) Infinity
c) Minimum
d) Zero
Correct Option: (a)
Explanation: Since the attraction on the North Pole of the needle is very strong, the angle of dip is 90o at the geographical North Pole, and the needle remains in the vertical plane. At the magnetic equator, the dip angle will be 0o because the needle will point horizontally. The angle increases in the northern hemisphere as you move from the magnetic equator towards the magnetic pole. Thus, the angle of dip will be maximum.
4) Around the Earth, the time period of the moon is 24 hours.
a) True
b) False
Correct Option: (b)
Explanation: The moon is not a geostationary satellite; therefore, around the Earth, the time period of the moon will not be 24 hours. However, it is found that nearly 27.3 Earth days is the time period of the moon around the Earth.
5) On the surface of the Earth, the acceleration due to gravity will be _____.
a) Lesser towards the poles and greater towards the equator
b) Greater towards the poles and lesser towards the equator
c) Same on the Earth
d) Apart from the poles, it will be the same everywhere
Correct Option: (b)
Explanation: The acceleration due to gravity is greater towards the poles and lesser towards the equator because we know that the Earth is not a perfect sphere and the radius of the Earth at the equator is greater as compared to the poles.
6) The magnitude of the acceleration due to the gravity for an object on the surface of the Earth depends on the mass of that object.
a) True
b) False
Correct Option: (b)
Explanation: According to the formula, g = (G*M1)/R2
Where M1 is the mass of the Earth,
The acceleration due to gravity only depends on the square of the distance between the object and the centre of the Earth and the mass of Earth for any object on the surface of the Earth.
7) Which among the following is the correct order of the different sections of the atmosphere?
a) Ionosphere>mesosphere>troposphere>atmosphere>exosphere
b) Atmosphere>mesosphere>ionosphere>exosphere>thermosphere
c) Exosphere>thermosphere>>mesosphere>stratosphere>troposphere
d) Mesosphere>thermosphere>stratosphere>troposphere>atmosphere
Correct Option: (c)
Explanation: The lowest region of the atmosphere is the troposphere, in which living organisms and human beings live. Between 10 and 50 km above the troposphere lies the stratosphere, the mesosphere, the thermosphere, and the exosphere.
8) Which among the following is not a gaseous form of air pollutant?
a) Ozone
b) Helium
c) Methane
d) Flumes
Correct Option: (d)
Explanation: Flumes contain solid particles in the form of a suspension in the air. It does not come under gaseous air pollutants; instead, it is a particulate pollutant. From different types of human activities, such particulate pollutants can be released. Other chemical plants’ fumes are also released from industries. Some examples of particulate pollutants are dust, smog, mist, smoke, etc.
9) The main constituents of acid rain among the following are _______.
a) Carbon, helium
b) Hydrogen, oxygen
c) Nitrogen, sulphur
d) Nitrogen, hydrogen and oxygen
Correct Option: (c)
Explanation: Oxides of nitrogen and sulphur are acidic, and they finally settle down either in water on the ground as dry deposition or fog. Therefore, acid rain contains the oxides of sulphur and nitrogen.
10) The average concentration of ozone in the ozone layer is _____.
a) Approximately 100%
b) More than 80%
c) Between 10-60%
d) Less than ten ppm
Correct Option: (d)
Explanation: In the ozone layer, the concentration of ozone is about ten ppm, and in the entire atmosphere, it is only 0.3 ppm.
Practice Questions
1) What is the universal law of gravitation?
2) Is the Earth flat or round?
3) How many layers are there in the atmosphere? Name them.
4) In which layer of the atmosphere do weather phenomena take place?
5) Ozone layer is located in which layer of the atmosphere?
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