If the half-life of a radioisotope is 20,000 years, then a sample in which three-quarters of that radioisotope has decayed is __
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Considering the definition of molar mass, the moles of gas used are 10.625 moles.
<h3>Definition of molar mass</h3>The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.
<h3>Amount of moles used</h3>Natural gas has a molar mass of 16.0 g/mole.
You started out the day with a tank containing 200.0 g of natural gas. So, you can apply the following rule of three: If by definition of molar mass 16 grams are contained in 1 mole, 200 grams are contained in how many moles?
<u><em>amount of moles at the beginning= 12.5 moles</em></u>
At the end of the day, your tank contains 30.0 g of natural gas. So, you can apply the following rule of three: If by definition of molar mass 16 grams are contained in 1 mole, 30 grams are contained in how many moles?
<u><em>amount of moles at the end= 1.875 moles</em></u>
The number of moles used will be the difference between the number of moles used initially and the contents at the end of the day.
moles used= amount of moles at the beginning - amount of moles at the end
moles used= 12.5 moles - 1.875 moles
<u><em>moles used= 10.625 moles</em></u>
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Finally, the moles of gas used are 10.625 moles.
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