Question

what is the number of oxygen atoms present in 126 g of HNO3​

Answer 1

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1 amu =1.66 x 10⁻²⁴grams(by definition)

126 amu =126(1.66 x 10⁻²⁴) grams

               =3.3 x 10⁻²⁴moles of HNO₃

1 mole of HNO₃ has 3 moles of Oxygen atoms.

3.3 x 10⁻²⁴moles of HNO₃ have 3(3.3 x 10⁻²⁴) atoms of oxygen atoms.

                                                = 9.9 x 10⁻²⁴ atoms of oxygen atoms.

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Answer 2

Answer:

Molecular mass of HNO3 =Atomic mass of Nitrogen +3× atomic mass of oxygen

= 1 + 14 +(3×16) =634

Number of moles = Given mass /

gram molecular mass

Moles of HNO3 = 126/63 = 2 moles

•In 1 molecule of HNO3 we have 3 atoms of O2.

•1 mole of HNO3 , we have 3 moles of Oxygen atoms . So , in 2 moles of HNO3 we will have 6 moles of O2 atoms .

• One mole of substance contains 6.022×10^23 particle. So , the No. of atoms in 126 g of HNO3

= 6× 6.023× 10^23= 36.132×10^23 atoms .

Hope this will help you ✌