What happens in a stationary front?
A. A warm air mass collides with a stationary cold air mass, and
slides under it B . A warm air mass catches up to a moving cold air mass, sliding
over it
C. A cold air mass and a warm air mass meet, with neither moving.
OD. A cold air mass catches up to a moving warm air mass.

c a cold air mass and a warm air mass meet with neither moving

the answer is   c.) 1575 j.

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"