According to two different estimates, coal reserves can be 250 Gt or 450 Gt, almost twice as much. Why is it so difficult to pin down the reserves' total?
What will be an ideal response?
Even with knowledge of geology and sampling techniques, all numbers of
unexploited resources are estimates. Local geology can lead to both over- and
underestimating. Sampling could miss a large part of a coal formation, leading to
underestimation, or encounter a small branch, assume it is part of a large formation, and lead
to an estimate that there is more than actually occurs.
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What will be an ideal response?
Which property of the Solar nebula was the most influential in giving the planets their characteristics?
A. temperature B. volume C. mass D. pressure
What is the period of revolution of a planet in circular orbit around a star of 4.0 solar masses if it is at a distance from the star equal to that of the Earth from the Sun?
The mean life (time constant) of radon-222 is 5.526 d. If a sample of radon initially contains 6.00 × 108 radon atoms, how many of them are left after 10.0 d?
A) 9.82 × 107 B) 7.67 × 107 C) 8.34 × 108 D) 7.29 × 108 E) 8.56 × 108