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2 years ago

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Light-colored rocks with lower densities form from basaltic magma. Please select the best answer from the choices provided T F

2 answers:

aliina [53]2 years ago

8 0

False thats what i just got on my test

slega [8]2 years ago

6 0

I believe the answer is false.

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Which climates are subcategories of temperate marine climates? Check all that apply.

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The answer is

B. Mediterranean
C. Humid Subtropical
E. Marine West Coast

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2 years ago

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What kind of fossil aging is used when scientists use the law of superposition?

-BARSIC- [3]

When scientists use the law of superposition to determine the age of a fossil, they go by the principle of 'every undisturbed layer of rock is older than the layer above it. This is not the most precise way of determining age, and in fact this method can only reveal the approximate age, but not the exact one.

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Calculate the amount, in grams, of an original 300-gram sample of radioactive isotope Potassium-40 remaining after

Aleksandr [31]

Answer:

The current amount of the Potassium-40 sample is approximately 37.521 grams.

Explanation:

The amount of the sample of the radioactive isotope decays exponentially in time, the amount of mass of the sample as a function of time ( $m (t)$ ), in grams, is described below:

$m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }$ (1)

Where:

$m_{o}$ - Initial mass, in grams.

$t$ - Time, in years.

$\tau$ - Time constant, in years.

The time constant can be found from half life ( $t_{1/2}$ ), in years, described in statement:

$\tau = \frac{t_{1/2}}{\ln 2}$ (2)

If we know that $m_{o} = 300\,g$ , $t = 3.9\times 10^{9}\,yr$ and $t_{1/2} = 1.3\times 10^{9}\,yr$ , then the current amount of the sample is:

$\tau = \frac{1.3\times 10^{9}\,yr}{\ln 2}$

$\tau \approx 1.876\times 10^{9}\,yr$

$m = (300\,g)\cdot e^{-\frac{3.9\times 10^{9}\,yr}{1.876\times 10^{9}\,yr} }$

$m\approx 37.521\,g$

The current amount of the Potassium-40 sample is approximately 37.521 grams.

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2 years ago

What causes temperatures of north/ south poles to stay cold?

IRISSAK [1]

The tilt of the earth’s axis, causing a further distance from the sun which reduces solar energy

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Geographers show population change over time by using: A. population pyramids B. death rates C. demography charts D. standard of

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I'm pretty sure they would show B. Death rates. Hope this helps!

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2 years ago