Answer:
The answer is tiny organisms known as cyanobacteria, or blue-green algae. These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and, yes, oxygen.
:-))
 
        
                    
             
        
        
        
Answer:
- Nitrogen has four pairs of electrons: 3 bonds and 1 lone pair in the valence shell;
 - Electrons repel one another based on the VSEPR theory;
 - Nitrogen has a total of 7 protons (its atomic number is 7) in its nucleus.
 
Explanation:
The shape and the bond orientation of molecules and ions are both explained by the valences shell electron pair repulsion theory (VSEPR).
Ammonia, 
, is a molecule which contains three N-H bonds, as well as one lone pair on nitrogen. According to the VSEPR theory, molecules try to acquire a shape which would minimize the repulsion exhibited by the electron clouds present, that is, between the bonding (shared in a bond) and non-bonding (lone pair) electrons.
In VSEPR, our main step is to calculate the steric number, this is the sum of the number of bonds (ignoring the multiplicity of any bond) and the lone pairs on a central atom. In ammonia, we have 3 bonds and 1 lone pair, totaling to a steric number of 4. A steric number of 4 without any lone pairs on a central atom and just bonds would yield a tetrahedral shape with bond angles of 
.
Now, in this case, since we have a lone pair instead of a bond, it is repelling stronger decreasing the bond angles to about 
.
The greater the number of lone pairs, the lower the angle becomes.
To summarize:
- Nitrogen has four pairs of electrons: 3 bonds and 1 lone pair in the valence shell;
 - Electrons repel one another based on the VSEPR theory;
 - Nitrogen has a total of 7 protons (its atomic number is 7) in its nucleus.
 
 
        
             
        
        
        
I would say C. Permable
Google def.(of a material or membrane) allowing liquids or gases to pass through it.
"a frog's skin is permeable to water
Porous- (of a rock or other material) having minute spaces or holes through which liquid or air may pass
        
                    
             
        
        
        
Answer:
C
Explanation:
If you move the decimal to the left it transforms the expression into scientific notation.
 
        
             
        
        
        
Cruising at 35,000 feet in an airliner, straight toward the east, 
at 500 miles per hour.  
Since your speed is not changing and you're moving in a straight line,
your acceleration is zero.