Answer
A. molecules
Explanation
When atoms or elements combine, they are called molecules. When molecules combine they form compounds.
Ice floats because it is about 9% less dense than liquid water. ... The heavier water displaces the lighter ice, so ice floats to the top. One consequence of this is that lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over
C. 2Fe2O3 would be the correct answer!
Energy, Temperature, and Changes of State
Matter either loses or absorbs energy when it changes from one state to another. For example, when matter changes from a liquid to a solid, it loses energy. The opposite happens when matter changes from a solid to a liquid.
The appropriate answer is b. greenhouse gases. Greenhouse gases such as carbon dioxide and methane have the ability to trap infrared radiation or heat in the atmosphere. Without these gases the Earth would be thirty degrees cooler than it is today. Pollution today has caused more of these gases to enter the atmosphere and this is the main cause of contemporary global warming.
Ozone in the stratosphere actually blocks another form of radiation called ultraviolet radiation. Geothermal energy is derived from hot rocks inside the earth.