Two scientists discuss the origin of Earth's oceans: * **Scientist 1** claims that Earth's… — ACT

Two scientists discuss the origin of Earth's oceans:

* Scientist 1 claims that Earth's water was delivered primarily by comets. Because comets from the outer solar system typically have high deuterium-to-hydrogen ( $D/H$ ) ratios, Earth's oceans should have a similarly high $D/H$ ratio.
* Scientist 2 claims that Earth's water originated from early volcanic outgassing of the Earth's mantle. Therefore, the $D/H$ ratio of Earth's oceans should be identical to the low $D/H$ ratio found in Earth's mantle.

Is the following statement true or false?

A study finding that the $D/H$ ratio of Earth's oceans is identical to the $D/H$ ratio of the Earth's mantle and significantly lower than that of comets supports Scientist 2's viewpoint.

Answer: Answer

Answer

The statement is true because the finding of a low deuterium-to-hydrogen (

D/H

) ratio in the oceans that matches the mantle directly aligns with the prediction of Scientist 2, who claims water originated from mantle outgassing.

Scientist 2 predicts that Earth's oceans will have a

D/H

ratio identical to that of the Earth's mantle. The finding that the ocean's

D/H

ratio is identical to the mantle's and lower than comets' directly supports Scientist 2's hypothesis.

Step-by-Step Solution

Identify the prediction of Scientist 2 regarding the deuterium-to-hydrogen (

D/H

) ratio of Earth's oceans.

Scientist 2 predicts that the

D/H

ratio of Earth's oceans will be identical to the relatively low

D/H

ratio of Earth's mantle.

Scientist 2 asserts that Earth's water originated from early volcanic outgassing of the mantle, meaning the water should carry the mantle's chemical signature.

Analyze the new experimental finding.

The study finds that the ocean's

D/H

ratio is identical to the mantle's

D/H

ratio and lower than that of comets.

This provides the empirical data point to compare against the predictions of both scientists.

Align the finding with the predictions to determine if the statement is true or false.

Because the observed ocean ratio matches the mantle ratio (as predicted by Scientist 2) and does not match the high comet ratio (as predicted by Scientist 1), the finding supports Scientist 2. Thus, the statement is true.

Comparing empirical data to scientific predictions allows us to evaluate which hypothesis the data supports.

Key Concept

Aligning Data and Predictions with Viewpoints

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Key Concept

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