One of the Major Differences Between Earth and Its Neighboring

question 207

Multiple Choice

One of the major differences between Earth and its neighboring planets Venus and Mars is the lack of large quantities of CO₂ in its atmosphere. If all three planets were originally formed with significant quantities of this gas in their atmospheres, where is the majority of this CO₂ on Earth at the present time?

• A) dissociated by UV and visible sunlight into carbon and oxygen that now exists in abundance as separate chemicals
• B) concentrated high in the atmosphere where it contributes to the greenhouse effect
• C) dissolved in seawater, a situation that cannot arise on the neighboring planets
• D) locked up in carbonate and carbon-rich rocks and minerals formed in the sea and on Earth's surface

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Definitions:

Contour Farming

An agricultural technique wherein farming practices are executed following the natural contours of the land, aimed at reducing soil erosion.

Terrace Farming

An agricultural practice of making flat areas or terraces on hilly terrain to prevent erosion and runoff, improve irrigation, and increase usable farming area.

Cover Crops

Plants grown primarily to benefit the soil and ecosystem, rather than for harvested crops, through means like erosion prevention and weed suppression.

Underground Water

Water that exists beneath the Earth's surface in soil pore spaces and in the fractures of rock formations, also known as groundwater.