What is the central atom of H2O?

Water has 4 regions of electron density around the central oxygen atom (2 bonds and 2 lone pairs). These are arranged in a tetrahedral shape. The resulting molecular shape is bent with an H-O-H angle of 104.5°.

Explanation:

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the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).

the transfer of heat by electromagnetic radiation is called thermal radiation . it is usually carried out by electromagnetic waves in an energy range just below the visible spectrum, which is the infrared range.

so the answer would be radiation.

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