Answer:
At a front, the two air masses have different densities, based on temperature, and do not easily mix. One air mass is lifted above the other, creating a low pressure zone.
Explanation:
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In a physical change the appearance or form of the matter changes but the kind of matter in the substance does not. However in a chemical change, the kind of matter changes and at least one new substance with new properties is formed. Hope this helps!
Answer: 404.04 kJ.
Explanation:
To calculate the moles, we use the equation:
moles of 
According to stoichiometry :
2 moles of on burning produces = 1036 kJ
Thus 0.78 moles of on burning produces =
Thus the enthalpy change when burning 26.7 g of hydrogen sulfide is 404.04 kJ.
