Answer: hydrogen
Explanation: hydrogen gas is a major component of water which occupies a large portion of the Earth's atmosphere
 
        
             
        
        
        
Answer:
Mitochondria is the powerhouse of the cell, but don't let this distract you from the fact that Mr. Krabs sold SpongeBob's soul for 62 cents
 
        
                    
             
        
        
        
Answer:- Mole ratio of D to A is 4:3.
Explanations:- Mole ratio for a chemical reaction is the ratio of the coefficients. 
The given generic chemical reaction is:

The numbers written in front of each chemical species in the chemical reaction are their moles. For the given generic chemical reaction the coefficient of A is 3 and that of B is 1. So, the mole ratio of A to B is 3:1.
Similarly if we want to write the mole ratio of C to D then it is 1:4.
We are asked to write the mole ratio of D to A. So, like the other ratios, the mole ratio of D to A is 4:3 as the coefficient of D is 4 and A is 3.
 
        
             
        
        
        
Answer:
11 electrons
Explanation:
The atomic number of sodium is 11. This tells us that sodium has 11 protons and because it is neutral it has 11 electrons. The mass number of an element tells us the number of protons AND neutrons in an atom (the two particles that have a measurable mass).