Cloudy skies and precipitation. Rain is normally caused by water vapor within the condensation of the low pressure system.
Answer:

Explanation:
Hello there!
In this case, according to the given information, it turns out necessary for us remember that the first-order kinetics is given by:

Whereas the 27.5% complete means A/Ao=0.275, and thus, we solve for the rate constant as follows:

Then, we plug in the variables to obtain:

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Answer:
0.4 moles
Explanation:
To convert between moles and grams you need the molar mass of the compound. The molar mass of of CaCO3 is 100.09g/mol. You use that as the unit converter.
40gCaCO3* 1mol CaCO3/100.09gCaCO3 = 0.399640 mol CaCO3
This rounds to 0.4 moles CaCO3
The answer is gonna be the last one :)