Answer:
A physical change effects a substance physically. Examples include cutting, bending, dissolving, freezing, boiling, and melting.
A chemical change effects a substance chemically. Examples include burning, rusting, and digesting.
Hope this helps.
 
        
             
        
        
        
Answer:
Protein.
Explanation:
In the image above, we see a molecule that is made up of several amino acids. The molecule that is made up of amino acids is protein.
Proteins are the most abundant organic macromolecules in cells, fundamental to cell structure and function. They are found in all cell types and viruses.
They are formed by amino acids linked together and joined by peptide bonds, as shown in the image above.
Of extremely high molecular weight, proteins are composed of carbon, hydrogen, nitrogen and oxygen, practically all of them have sulfur. Elements such as iron, zinc and copper may also be present.
All proteins are made up of a set of 20 amino acids, arranged in varying specific sequences.
 
        
             
        
        
        
Answer:
frequency✧C
wavelength✧A
wave speed✧D
wave period✧E
amplitude✧B
i'm not sure if they are all correct so sorry ✧
 
        
             
        
        
        
It Is The Melanoma Gene .
        
             
        
        
        
Answer:
Option D, A subject is observed both before and after two exposures to the treatment.
Explanation:
In A-B-A-B design the alphabets have following meaning
a)	First A – It is the baseline value or the value measured before treatment
b)	First B – It is the treatment measurement
c)	Second A  - It is the withdrawal of treatment  
d)	Second B – It is the reintroduction of treatment  
The second A is known as the reversal phase in which the intervention is withdrawn to see if the target behavior returns to the baseline behaviour
Thus , there are two measurements involved one before the intervention and second after the intervention
Option D is correct