A. Oxygen ion
I am not sure but that's the right one I think. If I am wrong then I am sorry
1.05moles
Explanation:
Given parameters:
Number of molecules of C₂H₆ = 6.29 x 10²³molecules
Unknown:
Number of moles = ?
Solution:
The mole is the amount of substances that contains Avogadro's number of particles i.e 6.02 x 10²³
To find the number of moles:
number of moles = 
number of moles = 
number of moles = 1.05moles
Learn more:
moles brainly.com/question/1841136
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Answer: New pressure inside the flask would be 148.8 kPa.
Explanation: The combined gas law equation is given by:

As the flask is a closed flask, so the volume remains constant. Temperature is constant also.
So, the relation between pressure and number of moles becomes



- Final conditions: When additional 3 puffs of air is added

Putting the values, in above equation, we get

Answer:
there are 20 oxygen atoms in 4.00 moles of Dinitrogen pentoxide
Explanation:
there are 2 atoms in an oxygen molecule , so each oxygen molecules has at least 2. Dinitrogen pentoxide is N2O5, which has 7 atoms, 2 nitrogen and 5 oxygen. 1 molecule of N2O5 has 5 oxygen atoms, so 4 of then would be 20
Cu(NO3)2>NO2+CuO+O2 balanced: 2Cu(NO3)2=4NO2+2CuO+O2