Class 9 Social Science: Chapter 3
- What is the most abundant gas in the Earth’s atmosphere?
A) Oxygen
B) Carbon dioxide
C) Nitrogen
D) Argon
Answer: C) Nitrogen. The Earth’s atmosphere is composed of a mixture of various gases, and nitrogen is the most abundant gas, making up 78% of it.
- In which layer of the atmosphere do nearly all weather phenomena, such as rainfall, fog, and hail, occur?
A) Stratosphere
B) Mesosphere
C) Troposphere
D) Thermosphere
Answer: C) Troposphere. The troposphere contains the air we breathe along with most of the water vapour and clouds, causing nearly all weather phenomena.
- Why is the stratosphere considered ideal for flying aeroplanes?
A) It contains a high amount of oxygen
B) It has a very high temperature
C) It reflects radio waves
D) It is free of clouds and other weather disturbances
Answer: D) It is free of clouds and other weather disturbances. Extending up to 50 kilometres, its stable conditions make it ideal for aviation.
- Which layer of the atmosphere contains the ozone gas that shields us from harmful ultraviolet radiation?
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Exosphere
Answer: B) Stratosphere. A notable feature of the stratosphere is that it contains a layer of ozone gas which acts as a protective shield against the Sun’s harmful radiation.
- What happens to most meteorites entering the Earth’s atmosphere from space?
A) They bounce off the Exosphere
B) They freeze in the Stratosphere
C) They burn up in the Mesosphere
D) They reflect off the Thermosphere
Answer: C) They burn up in the Mesosphere. The mesosphere extends up to 80 kilometres and burns up most incoming space debris.
- Which layer of the atmosphere helps with radio transmission by reflecting radio waves back towards Earth?
A) Stratosphere
B) Exosphere
C) Troposphere
D) Thermosphere
Answer: D) Thermosphere. The ionosphere is a part of this layer and reflects transmitted radio waves to aid in communication.
- In which layer of the atmosphere do the northern and southern lights (auroras) occur?
A) Troposphere
B) Stratosphere
C) Thermosphere
D) Mesosphere
Answer: C) Thermosphere. Auroras are created when solar wind interacts with different atmospheric gases in the thermosphere.
- What term refers to the sum total of weather conditions and variations over a large area for an extended period, usually thirty years or more?
A) Weather
B) Insolation
C) Climate
D) Humidity
Answer: C) Climate. While weather reflects day-to-day atmospheric conditions, climate tracks long-term averages over extended periods.
- What is the incoming solar energy intercepted by the Earth, which largely affects temperature distribution, called?
A) Humidity
B) Gravity
C) Insolation
D) Precipitation
Answer: C) Insolation. The amount of insolation decreases from the equator towards the poles, heavily influencing the Earth’s temperature.
- What type of weather is generally associated with a high-pressure area?
A) Cloudy skies and wet weather
B) Clear and sunny skies
C) Severe storms
D) Heavy snowfall
Answer: B) Clear and sunny skies. In areas with lower temperatures, the air is cold and heavy; it sinks, creating a high-pressure area associated with clear and sunny skies.
- When does a sea breeze primarily blow from the sea to the land?
A) During the day, especially in the afternoon
B) During the night, after sunset
C) Only during the winter season
D) Only during the monsoon season
Answer: A) During the day, especially in the afternoon. The land becomes warmer than the sea, creating a low-pressure region that draws in wind from the sea.
- The word ‘monsoon’ is derived from the word ‘mausim’. What language does this word originate from?
A) Latin
B) Arabic
C) Sanskrit
D) Greek
Answer: B) Arabic. Arab traders travelling to India observed the seasonal reversal of winds and coined the term from ‘mausim’, which literally means season.
- Traditionally, how many seasons is the year divided into according to the astronomical division in the Indian calendar?
A) 4
B) 5
C) 6
D) 12
Answer: C) 6. Traditional Indian seasons consist of spring (Vasanta), summer (Grishma), monsoon (Varsha), early autumn (Sharad), late autumn (Hemanta), and winter (Shishira).
- Which ancient text contains records of scientific measurements of rainfall and their practical application in managing revenue?
A) Meghadutam
B) Brihatsamhita
C) Kautilya’s Arthashastra
D) Krishiparashara
Answer: C) Kautilya’s Arthashastra. This text recorded rainfall measurements and detailed how they were used in managing the country’s revenue and relief efforts.
- Which 5th-century CE text by Kalidasa mentions the date of the onset of the monsoon over central India?
A) Meghadutam
B) Brihatsamhita
C) Arthashastra
D) Krishiparashara
Answer: A) Meghadutam. This historical text traces the path of monsoon clouds and mentions the onset dates.
- During the winter monsoon (north-east monsoon), which Indian regions receive important rainfall?
A) Punjab and Haryana
B) Rajasthan and Gujarat
C) Tamil Nadu, Andhra Pradesh, and parts of Karnataka
D) Jammu and Kashmir
Answer: C) Tamil Nadu, Andhra Pradesh, and parts of Karnataka. As winds pass over the Bay of Bengal, they pick up moisture and cause rainfall in the south-eastern regions.
- What is the term for the total amount of greenhouse gases released into the atmosphere as a result of human activities?
A) Carbon footprint
B) Insolation
C) Atmospheric pressure
D) Ozone depletion
Answer: A) Carbon footprint. It calculates the impact of activities like energy use, transportation, and production of goods on the atmosphere.
- In 2025, which Indian state experienced severe floods due to heavy monsoon rains and the swelling of the Satluj, Beas, and Ravi rivers?
A) Kerala
B) Assam
C) Punjab
D) Bihar
Answer: C) Punjab. Heavy monsoon rains and the consecutive swelling of these rivers caused devastating floods in the state.
- What local term is used for the river embankments that were weak and failed to stop the rising water during the 2025 Punjab floods?
A) Nakshatras
B) Dhusi bandh
C) Vasanta
D) Mausim
Answer: B) Dhusi bandh. The failure of these old embankments was a major human-made cause that worsened the flooding.
- Which Government of India mission aims to make the nation ‘Weather Ready’ and ‘Climate Smart’?
A) Mission Nakshatra
B) National Flood Mission
C) Mission Mausam
D) Mission Aurora
Answer: C) Mission Mausam. This initiative seeks to improve weather and climate services across agriculture, disaster management, and rural development globally.
- What happens to the air’s capacity to hold water vapour as its temperature gets warmer?
A) It decreases
B) It remains the same
C) It completely drops to zero
D) It increases
Answer: D) It increases. As air gets warmer, its capacity to hold water vapour increases, leading to higher humidity levels.
- In which two layers of the atmosphere does temperature exclusively decrease with increasing altitude?
A) Stratosphere and Thermosphere
B) Troposphere and Mesosphere
C) Exosphere and Stratosphere
D) Mesosphere and Thermosphere
Answer: B) Troposphere and Mesosphere. The temperature decreases with altitude only within the troposphere and mesosphere.
- What percentage of the Earth’s atmosphere consists of Oxygen?
A) 78%
B) 21%
C) 0.93%
D) 0.04%
Answer: B) 21%. Oxygen is the second most abundant gas and makes up 21% of the atmosphere.
- Nakshatras divide the sky into how many equal parts?
A) 12
B) 24
C) 27
D) 30
Answer: C) 27. Nakshatras are a way of dividing the sky into 27 equal parts along the path the Moon travels.
- Which is the uppermost layer of the atmosphere where light gases like helium and hydrogen float into space?
A) Troposphere
B) Stratosphere
C) Thermosphere
D) Exosphere
Answer: D) Exosphere. The uppermost layer is known as the exosphere, characterised by very thin air and weak gravity.