Why is it that scientists know less about the first four-fifths of Earth's history than about the last, most recent one-fifth?
What will be an ideal response?
Answer: The short answer is that the farther back in time, the fewer the clues that remain because of two major factors: 1) Precambrian rocks (which make up 88 percent of Earth's history) have been intensely deformed, so evidence was destroyed, and 2) the first abundant fossil evidence does not appear until the beginning of the Cambrian period.
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A 1-kg chunk of slime moving at 1 m/s collides and sticks to a 5-kg bowling ball initially at rest. The momentum of the combined ball and slime is
A. 0 kg?m/s. B. 5 kg?m/s. C. 1 kg?m/s. D. 2 kg?m/s.
In the process of getting energy to power your television, which of the following stages is the most energy efficient?
A. Thermal conversion of the energy from coal in the power plant B. Burning the coal to run the power plant C. Actually powering your television set D. Transmission to your house E. Mining the coal to run the power plant
CO2 reacts with water to form _______________, which makes the ocean more acidic
Fill in the blank with correct word.
Why is cation-exchange capacity (CEC) an important soil characteristic?
A) CEC is an indication of the soil permeability; the lower the CEC the higher the permeability. B) CEC is used to infer soil texture without having to use a soil texture triangle. C) CEC is an indirect way to measure soil pH; it indicates whether the soil is neutral, alkaline, or acidic. D) CEC is a measure of soil fertility; the higher the CEC the higher the soil fertility.