Unfortunately, Mr. M. Subramanian, who maintained this website lost his battle to cancer and passed away in July, 2019. The database has over 50,000 questions. If you are interested in purchasing the website/database, please reach out using the form here. Learn TNPSC exam and online pratice


Q1. What is an Atmosphere?
It is a mixed gaseous and water vapour envelope that surrounds the celestial body upto 480 Kms.
Q2. What is the most common and abundant gas found in the Earth's atmosphere?
Nitrogen 78.09%.
Q3. What is the importance of Atmosphere to the existence of living organisms?
It controls the temperature on Earth. Protects the living organisms from the Ultraviolet rays.
Q4. What is the thickness of Atmosphere?
Upto 960 Kms above the Earth.
Q5. What is the approximate weight of air in the Atmosphere?
Six multiplied by ten to the power of 15 is the approximate weight of air in the atmosphere.
Q6. What is the content of Atmosphere?

Nitrogen 78.09%

Oxygen 20.95%

Argon 0.93%

Others 0.03%.

Others include Carbon-di-oxide, Hydrogen, Neon, Helium, Methane, Xenon and Krypton.

Q7. Beyond 50 Kms from Earth, in the atmosphere, what are the contents of air?
Atomic Oxygen, Ozone, Helium and Hydrogen.
Q8. What is "Atmospheric Pressure"?
Weight of the entire air column over a given point.
Q9. What is the weight of one litre of air?
1.3 Grams.
Q10. What is the common term for the amount of water vapour that is held in the air?
Q11. What is the presence of air at sea level?
Around 1033.6 gms per cm squire.
Q12. Atmosphere is divided into how many spheres and pauses and what are they?



  1. Troposphere
  2. Stratosphere
  3. Mesosphere
  4. Ionosphere
  5. Thermosphere
  6. Exosphere and
  7. Magnetosphere.



  1. Tropopause
  2. Mesopause and
  3. Magnetopause.
Q13. What is 'Troposphere' and what is its extant?
Atmosphere nearest to the earth's surface and its extant is 15 Kms in altitude from the sea level.
Q14. What is the content of Troposphere?
Water Vapour, Moisture and Dust particles.
Q15. What happens to the temperature as the altitude in Troposphere increases?
Temperature decreases as the altitude of troposphere increases.
Q16. What is the extant of Stratosphere?
15 to 50 Kms above sea level.
Q17. What is the temperature at Stratosphere?
Q18. What is the content of Stratosphere?
Water vapour, moisture and dust particles.
Q19. What is Tropopause?
The layer that separates or remain between Troposphere and Stratosphere.
Q20. What sphere lies above the Tropopause?
Q21. What is Mesosphere?
The layer of atmosphere beyond 50 and below 85 Kms above sea level.
Q22. What is the climate at Mesosphere?
Very cold.
Q23. What is the content of Mesosphere?
Extremely dry and traces of water vapour present during summer months.
Q24. What is Ionosphere?
The atmosphere lying between 80 to 400 Kms above sea level.
Q25. What is the content of Ionosphere?
Ionised air - electrically charged air.
Q26. How the Ionosphere helps the earth?
  1. It protects the earth from falling meteorites as they get burnt out here.
  2. Protects the earth from radiation reaching the earth.
Q27. What is Mesopause?
Layer of atmosphere separating Mesosphere and Ionosphere.
Q28. What is Thermosphere?
Middle layer of Ionosphere.
Q29. Where is Exosphere?
Uppermost region of the Ionosphere. It is the outer limits of the atmosphere. Gravity of the Earth is very weak here.
Q30. What is Magnetosphere?
The magnetic belt of the Earth extending upto 64000 Kms above sea level.
Q31. What is Magnetopause?
The final bounday between Earth and the outer space.
Q32. Arrange the spheres and pauses in the order in which they exist above earth?






6.Ionosphere includes Thermosphere in the middle

7.Exosphere - the upper most layer of Ionosphere

8.Magnetosphere     and

9.Magnetopause. Beyond this it becomes outer space.

Q33. What is Ozone layer?
The Stratosphere is called so - 15 to 50 Kms above sea level because it contains Ozone gas.
Q34. What is the use of Ozone layer?
Protects the manking from harmful radiation called Ultraviolet by absorption.
Q35. Which gas causes the depletion of Ozone layer?
Chloro Fluoro Hydrocarbons -CFC.
Q36. What are the sources of CFC emission?
  1. Air Conditioners
  2. Refrigerators
  3. Aerosols
  4. Solvents
  5. Production of certain packaging materials
  6. Nitrous Oxide Fertilisers  (and)  
  7. Aircraft emissions.
Q37. What is Aerosol?
A suspension of colloidal particles in gas.
Q38. What are the effects of depletion of ozone layer?
Skin Cancer, Severe sunburns and damages on vegetation.
Q39. In simple terms, what is Green House Effect?
The process by which an atmosphere warms a planet. Carbon-di-oxide is the cause of this.
Q40. What is the distance from the ground that is recognised as the boundary of Space by the Federation Aeronautique Internationale?
100 Kms.
Q41. What is TSPM related to Atmosphere?
Total Suspended Particulate Matter. A method of assessing the level of pollution in the air, that is, the amount of TSPM in a particular place, more or less of the permissible limit.


Q42. What is a Comet?
It consists of a Coma made up of hot gas and dust. It is small in size. From the head flows a tail consisting streams of dust and gas.
Q43. Approximately how many comets are there in the solar system?
About one lakh.
Q44. Who identified the famous Hailey's Comet?
Edmund Hailey, UK.
Q45. What is the periodicity of the appearance of the Hailey's comet?
75/76 years.
Q46. When did Hailey's comet appear last?
Q47. When Hailey's comet is expected to appear again?
2062 (anytime from July 2061)
Q48. Which comet is likely to collide with Earth?
Comet Smith Tuttle - Around August 17, 2116.
Q49. When was Comet Smith Tuttle discovered and what is it made of?
It was first sighted in 1862 and rediscovered in September 1992. It is made up of ice and rock.
Q50. What will be the magnitude of effect on earth if the expected collision of Comet Smith Tuttle take place as forecast?
May cause an impact of 1.6 million times the force of Hiroshima Atomic Bomb (nearly 20 million megatons)
Q51. Who discovered the Comet Showmaker Levy?
Carolyn and Eugene Shoemaker and David Levy in 1993.
Q52. How big is the Shoemaker Levy Comet?
10 Kms in length and weighs about 500 million tons.
Q53. To which planet the Comet Shoemaker Levy 9 came closer in July 1994?
Jupiter - between 16th to 21st July 1994.
Q54. What happened to the Comet Shoemaker Levy 9 when it came closed to Jupiter in July 1994?
Broke into 21 pieces and entered into Jupiter.
Q55. Which comet is expected to appear in 2011?
Q56. What is the latest comet to be discovered?
Comet Mc.Naught discovered on 7.8.2006 called as Great Comet 2007.
Q57. What are the comets that have appeared in the recent past?
1. Hailey - 1986-86; 2. D'Arrest - 1986; 3. Encke - 1987; 4. Borelly 1987; 5. Ponns Winnecke - 1988; 6.Finlay - 1988; 7. Faye - 1990 and 8. Smith Tuttle in 1994.
Q58. Which comet is expected to reapper in 2356?
Great Comet - The tail of this comet is 330 million Kms long.


Q59. What is an Eclipse?
When the light of the Sun or Moon is obscured by one another, it is called so.
Q60. What are the regular Eclipses?
Solar and Lunar.
Q61. What is a Lunar Eclipse and When it occurs?
Eclipse of the Moon. It occurs when the Earth comes between the Moon and the Sun. The shadow cast on the Earth by the Moon is called the Lunar Eclipse. It occurs only on a Full Moon Day.
Q62. Why does the Lunar Eclipse not occur on every Full Moon Day?
Because the Moon is not in the same position in relation to the Earth and the Sun on every full moon day.
Q63. What is a solar Eclipse?
When the Moon comes between the Sun and the Earth it is called so.
Q64. Solar Eclipse occurs on?
New Moon Day. It may be partial or full eclipse.
Q65. What is the longest recorded solar eclipse of the 20th century?
7mts and .8 seconds on 20.6.1955
Q66. Why does the Solar Eclipse not occur on all New Moon Days?
Due to the inclination of Moon's orbit.
Q67. What is an Annular Eclipse?
It is when the Sun and the Moon are exactly in line, but the apparent size of the Moon is smaller than that of Sun.
Q68. A triple eclipse in a year is a rare astronomical occurrence. However, they have occurred on a few occasions with some important events.What are they?
  1. 3031 BC Ancient city of Dwaraka destroyed.
  2. 1914 - World War I
  3. 1939 - World War II
  4. 2009 - On July 22 and August 6th, with two lunar eclipses within 30 days. A rare occurrence.
Q69. What was the recently occurred annular solar eclipse which is a record?
This millenium's longest annular solar eclipse occurred on January 15,2010A. This millenium's longest annular solar eclipse occurred on January 15,2010 and was visible in the southern districts of Tamilnadu. It lasted for 11 minutes and 7.8 seconds. This record is likely to lass till December 3043.
Q70. What are the types of eclipses?
TOTAL ECLIPSE: Occurs when the Sun is completely obscured by the Moon, in that in its fullness, much fainter corona alone will be visible.
ANNULAR ECLIPSE: Occurs when the Sun and Moon are exactly in line, but the apparent size of the Moon is smaller than that of the Sun.
HYBRID ECLIPSE: Also called annular/total eclipse, transitions between a total and annular eclipse. At some points on the surface of the Earth it is visible as a total eclipse, whereas at others it is annular. Hybrid eclipses are comparatively rare.
PARTIAL ECLIPSE: Occurs when the Sun and Moon are not exactly in line and the Moon only partially obscures the Sun. This phenomenon can usually be seen from a large part of the Earth outside of the track of an annular/total eclipse. However, some eclipses can only be seen as a partial eclipse, because the umbra never intersects the Earth's surface, passing above the Earth's polar regions.