-. You have 100 grams of methane. How many moles do you have?

6.25mol

Explanation:

Using the following formula;

Mole = mass ÷ molar mass

According to this question, there are 100 grams of methane (CH4)

Molar Mass of methane (CH4) = 12 + 1(4)

= 12 + 4

= 16g/mol

mole = 100/16

mole = 6.25moles

Therefore, there are 6.25moles of methane in 100g

"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"