The answer is Sodium  Fluoride 
        
                    
             
        
        
        
Answer:
Within double-stranded DNA, the nitrogenous bases on one strand pair with complementary bases along the other strand; in particular, A always pairs with T, and C always pairs with G. Then, during DNA replication, the two strands in the double helix separate.
Explanation:
The four nitrogenous bases of DNA are thymine, adenine, guanine, and cytosine. Guanine and cytosine are bound together by three hydrogen bonds; whereas, adenine and thymine are bound together by two hydrogen bonds. This is known as complementary base pairing.
 
        
             
        
        
        
If you mean periodic table then it would be atomic number
        
             
        
        
        
Answer:
1.Carbon is the basis of all living things
3.Nitrogen is found in certain foods
4.Oxygen and hydrogen combine with each other to form water
6.Carbon, oxygen, hydrogen, nitrogen, phosphorus and sulfur are found in organic compounds
Explanation:
 
        
                    
             
        
        
        
Answer: Sickle cell disease is caused by a mutation in the hemoglobin-Beta gene found on chromosome 11. Hemoglobin transports oxygen from the lungs to other parts of the body. Red blood cells with normal hemoglobin (hemoglobin-A) are smooth and round and glide through blood vessels.
Explanation: