Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

[EX Q]: Question: Which currents distribute heat around the planet and have a large impact on climate? Answer: surface
[EX A]: Surface currents are extremely important because they distribute heat around the planet. Surface currents also have a tremendous influence on climate around the globe.

[EX Q]: Question: Isothermal expansion is a process occurring without a change in? Answer: temperature
[EX A]: isothermal expansion is a process occurring without a change in temperature.

[EX Q]: Question: How many valence electrons does carbon have? Answer: four
[EX A]:
Carbon has four valence electrons, so it can achieve a full outer energy level by forming four covalent bonds. When it bonds only with hydrogen, it forms compounds called hydrocarbons.