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Science - Class 9
ScienceClass 9

Science

Basic science concepts for Class 9

Previous Year Questions

Practice questions from Science Science

1

Which of the following adds carbon dioxide to the carbon cycle on the planet Earth?

  1. Volcanic action
  2. Respiration
  3. Photosynthesis
  4. Decay of organic matter

Select the correct answer using the code given below.

A. 1 and 3 only
B. 2 only
C. 1, 2 and 4 only(Correct Answer)
D. 1, 2, 3 and 4

The carbon cycle is a crucial process that involves the movement of carbon among the atmosphere, oceans, soil, and living organisms. Several natural processes contribute to the addition of carbon dioxide (CO2) into this cycle:

  • Volcanic action: Volcanic eruptions release significant amounts of carbon dioxide into the atmosphere.
  • Respiration: All aerobic organisms, including humans, release carbon dioxide as a byproduct of respiration.
  • Photosynthesis: This process, performed by plants, algae, and some bacteria, actually removes carbon dioxide from the atmosphere, rather than adding it.
  • Decay of organic matter: The decomposition of dead organisms by microbes releases carbon dioxide back into the atmosphere.

In summary, the processes that add carbon dioxide to the carbon cycle are volcanic action, respiration, and decay of organic matter.

Source: 11th NCERT: Geography Chapter

2

In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following?

  1. Area of the hole in the lid
  2. Temperature of the flame
  3. Weight of the lid

Select the correct answer using the code given below.

A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only(Correct Answer)
D. 1, 2 and 3

Inside a pressure cooker, the boiling point is increased by increasing the pressure. Hence, cooking is faster. Therefore, the temperature at which food is cooked is affected by the pressure and not the temperature of the flame.

This can also be understood by understanding why cooking is difficult on hills. At high altitudes, atmospheric pressure is lower, reducing the boiling point of water as compared to that at sea level.

Source: NCERT

3

Which of the following adds carbon dioxide to the carbon cycle on the planet Earth?

  1. Volcanic action
  2. Respiration
  3. Photosynthesis
  4. Decay of organic matter

Select the correct answer using the code given below.

A. 1 and 3 only
B. 2 only
C. 1, 2 and 4 only(Correct Answer)
D. 1, 2, 3 and 4

The carbon cycle is a crucial process that involves the movement of carbon among the atmosphere, oceans, soil, and living organisms. Several natural processes contribute to the addition of carbon dioxide (CO2) into this cycle:

  • Volcanic action: Volcanic eruptions release significant amounts of carbon dioxide into the atmosphere.
  • Respiration: All aerobic organisms, including humans, release carbon dioxide as a byproduct of respiration.
  • Photosynthesis: This process, performed by plants, algae, and some bacteria, actually removes carbon dioxide from the atmosphere, rather than adding it.
  • Decay of organic matter: The decomposition of dead organisms by microbes releases carbon dioxide back into the atmosphere.

In summary, the processes that add carbon dioxide to the carbon cycle are volcanic action, respiration, and decay of organic matter.

Source: 11th NCERT: Geography Chapter

4

Which of the following is/are the example/examples of chemical change?

  1. Crystallization of sodium chloride
  2. Melting of ice
  3. Souring of milk

Select the correct answer using the code given below.

A. 1 and 2 only
B. 3 only(Correct Answer)
C. 1, 2 and 3
D. None

Crystallization of sodium chloride and melting of ice are physical changes as they involve a change of state. Souring of milk is a chemical change because it results in the formation of new substances.

Source: 7th NCERT: Science Chapter

5

Which of the following adds carbon dioxide to the carbon cycle on the planet Earth?

  1. Volcanic action
  2. Respiration
  3. Photosynthesis
  4. Decay of organic matter

Select the correct answer using the code given below.

A. 1 and 3 only
B. 2 only
C. 1, 2 and 4 only(Correct Answer)
D. 1, 2, 3 and 4

The carbon cycle is a crucial process that involves the movement of carbon among the atmosphere, oceans, soil, and living organisms. Several natural processes contribute to the addition of carbon dioxide (CO2) into this cycle:

  • Volcanic action: Volcanic eruptions release significant amounts of carbon dioxide into the atmosphere.
  • Respiration: All aerobic organisms, including humans, release carbon dioxide as a byproduct of respiration.
  • Photosynthesis: This process, performed by plants, algae, and some bacteria, actually removes carbon dioxide from the atmosphere, rather than adding it.
  • Decay of organic matter: The decomposition of dead organisms by microbes releases carbon dioxide back into the atmosphere.

In summary, the processes that add carbon dioxide to the carbon cycle are volcanic action, respiration, and decay of organic matter.

Source: 11th NCERT: Geography Chapter

Previous Year Questions

Test your knowledge with these practice questions

Question 1 of 50 / 5 answered
1

Which of the following adds carbon dioxide to the carbon cycle on the planet Earth?

  1. Volcanic action
  2. Respiration
  3. Photosynthesis
  4. Decay of organic matter

Select the correct answer using the code given below.

Year: 2014

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