Question

which of the following is a correct example of how a change in the temperature of the atmosphere has caused a change in the composition of the atmosphere?
when the earth was heated, the first type of photosynthesis could occur and made oxygen.
when the earth was heated, hydrogen was sent out into space and out of the atmosphere.
when the earth cooled, volcanoes became more frequent and sent out more carbon dioxide.
when the earth cooled, water vapor condensed into liquid creating the oceans.

Explanation:

Step1: Analyze Option A

Photosynthesis is a biological process (not directly a temperature - induced change in atmosphere composition). It is the process by which plants use light energy to convert carbon dioxide and water into glucose and oxygen. The key factor for the first photosynthesis was the evolution of photosynthetic organisms, not just heating.

Step2: Analyze Option B

When the Earth was very hot (in its early stages), lighter gases like hydrogen had high thermal velocities. According to the kinetic theory of gases, \(v = \sqrt{\frac{3RT}{M}}\) (where \(v\) is the root - mean - square speed, \(R\) is the gas constant, \(T\) is temperature, and \(M\) is molar mass). Since hydrogen has a very low molar mass (\(M = 2\space g/mol\)), at high temperatures (high \(T\)), its speed could exceed the Earth's escape velocity (\(v_{escape}=\sqrt{\frac{2GM}{r}}\), where \(G\) is the gravitational constant, \(M\) is the mass of the Earth, and \(r\) is the radius of the Earth). So, hydrogen was lost from the atmosphere due to heating.

Step3: Analyze Option C

When the Earth cooled, volcanic activity decreased over time. In the early, hot Earth, volcanic activity was more intense. As the Earth cooled, the interior also cooled down, and the frequency and intensity of volcanic eruptions (which release gases like carbon dioxide) decreased.

Step4: Analyze Option D

When the Earth cooled, water vapor condensing into liquid (to form oceans) is a physical change (phase change of water) and not a change in the composition of the atmosphere in terms of chemical species. The water was already present in the atmosphere as vapor.

Answer:

B. When the Earth was heated, hydrogen was sent out into space and out of the atmosphere.