The body tolerates a wide range of many variables such as blood glucose and sodium plasma levels. Why do you think that is there much less variation tolerated in oxygen saturation? Normal ranges:
Glucose 90-130 mg/dL
Plasma-sodium 135 and 145 (mEq/L)
Oxygen 95-100% saturation
There is much less variation tolerated in oxygen saturation because

I do not know and also you are from bryant Hs Right?

Explanation:

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

there is none because earth is stationary and flat.