Which equation represents a double replacement reaction? A) 2 Na + 2 H2O → 2 NaOH + H2
B) CaCO3 → CaO + CO2
C) LiOH + HCl → LiCl + H2O
D) CH4 + 2 O2 → CO2 + 2 H2O

C) LiOH + HCl → LiCl + H₂O

General Formulas and Concepts:

Chemistry - Reactions

Explanation:

Step 1: Define

RxN A:   2Na + 2H₂O → 2NaOH + H₂

RxN B:   CaCO₃ → CaO + CO₂

RxN C:   LiOH + HCl → LiCl + H₂O

RxN D:   CH₄ + 2O₂ → CO₂ + 2H₂O

Step 2: Identify

RxN A:   Single Replacement Reaction

RxN B:   Decomposition Reaction

RxN C:   Double Replacement Reaction

RxN D:   Combustion Reaction

"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"

i don't see a text, but i am gonna assume this *orbit* the curved path, usually elliptical, described by a planet, satellite, spaceship, etc., around a celestial body, as the sun.