25. What is the percentage by mass of nitrogen in copper(II) nitrate? a. 14.93%
b. 33.88%
c. 50.61%
d. 44.40%

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles

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is there any options? maybe im just not seeing them but i need the options to

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