Compounds consist of atoms of different elements. In compound the atoms are present in fixed proportion. By changing the proportion compound will changed. For example,
Nitrogen and oxygen reacted to form the compound. By changing the proportion both will form different compound.
NO₂
Nitrogen dioxide consist of one atom of nitrogen and two atoms of oxygen. Their ration is 1 :2
NO
In nitric oxide one atom of oxygen and one atom of nitrogen are present.
Their ratio is 1 : 1.
N₂O
Nitrous oxide consist of two nitrogen atoms and one oxygen. Their ratio is
2 : 1
N₂O₄
Dinitrogen tetroxide consist of two nitrogen atoms and four oxygen atoms. Their ratio will written as 2 : 4
N₂O₅
Dinitrogen pentoxide consist of two nitrogen atoms and five oxygen atoms. Their ratio will written as 2 : 5
 
        
             
        
        
        
I’d say the last one, the cancer cells lack inhibition and the do not stop reproducing. The rest of the answers don’t really make sense. The cancer cells can be controlled with chemotherapy so the first one is definitely wrong. And I do not believe that they contain stem cells. The last one is right because the reason cells become cancerous is because their growth inhibitors are broken or switched off, so they do not know when to stop growing and it becomes a problem for the body.
        
                    
             
        
        
        
The answer is; catalyst
These proteins are called enzymes. They work by lowering the activation energy of reactants and hence speed up the biochemical reaction. They are not affected in the process hence one enzyme molecule can catalyze many reactions. An example of such an enzyme is carbonic anhydrase that enables carbon dioxide to dissolve in blood plasma as carbonic acid. 
 
        
             
        
        
        
Answer: Conduction
Explanation: As the fire starts to heat up the metal hanger it transfers the heat onto your hand. 
Conduction Def: The process by which heat or electricity is directly transmitted through a substance
 
        
             
        
        
        
Answer:
C) It involves interactions between biotic and
abiotic factors.
Explanation:
Ecosystems need energy imput, need both consumers and producers, and can exist on land, lakes, rivers and oceans.