Non-renewable energy sources are sources that will run out in our lifetimes and for the following lifetimes. Coal is a non-renewable resource. It is a black or brownish rock that produces energy when burned. Oil is a non-renewable energy. Oil is a liquid fossil fuel. Oil can be access through drilling the earth’s crust or the ocean floor. Wood is a renewable resource. The seeds can be planted again to create more trees and obtain wood. Natural gas is a non-renewable resource. It is found a few hundred meters underground. It is mostly made up of methane.
        
                    
             
        
        
        
Explanation:
here your answer
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The lac repressor protein is bound to the operator region of the lac operon when there is no lactose in the medium. When introduced in lactose, it binds to an allosteric site on the repressor causing its to change conformation and release from the operator. This allows the polymerase that is bound to the promoter region to proceed transcription of the lac operon genes (LacZ, Lac A, and Lac Y). Translation of these genes forms enzymes that enable the organism to break down lactose for energy.   
 
        
             
        
        
        
Answer:
O silicon (Si)
Explanation:
-Valence electrons are electrons of the outermost shell which can participate in chemical bonding. ... -As in silicon, four electrons are present in the outermost shell, so silicon has Four valence electrons.