Carbon Cycle — Homi Bhabha Exam Chemistry MCQs with Solutions
Free Homi Bhabha Exam Chemistry Carbon Cycle MCQs with step-by-step solutions (8 questions). Part of Carbon & Its Compounds. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Carbon Cycle · medium · theory
The carbon cycle describes the continuous exchange of carbon among the atmosphere, plants, animals and:
A. the soil and oceans ✓ Correct
B. outer space
C. the Sun
D. the Moon
Solution: Carbon circulates among air, living things, soil and oceans in the carbon cycle.
Q2 — Carbon Cycle · medium · theory
The process by which green plants remove carbon dioxide from the atmosphere is:
A. combustion
B. photosynthesis ✓ Correct
C. decomposition
D. respiration
Solution: During photosynthesis, plants take in CO₂ to make food, removing it from the air.
Q3 — Carbon Cycle · hard · theory
Which processes ADD carbon dioxide to the atmosphere?
A. Respiration and combustion of fuels ✓ Correct
B. Photosynthesis only
C. Filtration
D. Condensation and melting
Solution: Respiration by living things and the burning of fuels both release CO₂.
Q4 — Carbon Cycle · hard · theory
The increasing concentration of carbon dioxide in the atmosphere due to burning of fossil fuels leads to:
A. more rainfall everywhere
B. a decrease in temperature
C. thicker ozone layer
D. global warming (enhanced greenhouse effect) ✓ Correct
Solution: Extra CO₂ traps more heat, raising global temperatures (global warming).
Q5 — Carbon Cycle · medium · theory
Fossil fuels such as coal and petroleum were formed from:
A. sea salt
B. melted rocks
C. the remains of dead plants and animals over millions of years ✓ Correct
D. volcanic lava
Solution: Fossil fuels formed from buried remains of ancient organisms under heat and pressure over ages.
Q6 — Carbon Cycle · medium · theory
The gas released back into the air by both plants and animals during respiration is:
A. carbon dioxide ✓ Correct
B. nitrogen
C. hydrogen
D. oxygen
Solution: Respiration uses oxygen and releases carbon dioxide.
Q7 — Carbon Cycle · hard · theory
The decomposition of dead plants and animals by microbes returns carbon to the environment mainly as:
A. oxygen
B. pure carbon
C. nitrogen gas
D. carbon dioxide ✓ Correct
Solution: Decomposers break down organic matter, releasing CO₂ back into the cycle.
Q8 — Carbon Cycle · medium · theory
Green plants play a key role in the carbon cycle because they:
A. produce fossil fuels directly
B. absorb nitrogen from air
C. fix atmospheric carbon dioxide into food ✓ Correct
D. release carbon dioxide only
Solution: Plants convert atmospheric CO₂ into carbohydrates through photosynthesis, fixing carbon.