Answer:
Diamond is the hardest mineral
Explanation:
mohs scale has been used worldwide to test the hardness of a mineral.Because it is cheap,easy to do and understood instantly. Other hardness test never gain that much popularity as Mohs scale.Its a relative integer scale comparison of being scratched. Other hardness test in which a specific pressure applied for a specific length of time.An example of a mineral with variable hardness is kaynte. Another best example is diamond with variable hardness people who cut diamond have known its variable hardness, In Mohs scale of hardness diamond 's position is number 10-10000 is its hardness.
 
        
                    
             
        
        
        
Answer:
I have been to get a 
Explanation:
I c have a true conclusion for my head but I think it is a good way for me to get 
 
        
             
        
        
        
Answer:
They grow more slowly, reproduce less, and populations decline.
Explanation:
brainliest plzzzzzzzzzzzzzzzzzzzzzzz
 
        
             
        
        
        
The four important characteristics of respiratory surface are:
1.	Thin walls
2.	Moisture
3.	Large surface area
4.	Blood supply
Respiratory system or respiratory tract is divided into upper and lower tract. Upper respiratory tract includes nose and its cavities, sinuses, pharynx and the part of the larynx. Lower respiratory tract consists of the trachea, bronchi, bronchioles and the alveoli.
Alveoli are the ends of the respiratory tract the smallest units in it. Alveoli are small folded air sacs that are branching off from alveolar ducts and providing an extremely large surface area for the gas exchange. Gas exchange occurs thanks to small blood vessels – capillaries that surround alveoli and it occurs via the process of diffusion.
So, respiratory surface is thin membrane also known as the blood–air barrier that consists of the alveolar epithelial cells, their basement membranes and the endothelial cells of the alveolar capillaries.