Question

If we assume that one-sixth the mass of an atom of 12C isotope is taken as the reference, the mass of one molecule of oxygen will:

• A. (A) Be double its original value
• B. (B) Be half its original value
• C. (C) Be the same
• D. (D) Increase by four fold

Answer 1

Answer: (C)

(C) Be the same

Answer 2

Explanation:
If we assume that one-sixth the mass of an atom of 12C isotope is taken as the reference, the mass of one molecule of oxygen will be the same.We know that: 12 g of Carbon =6.023×1023 atomsSo, 1g=6.023×102312∴6g of carbon =6×6.023×102312=12×6.023×1023This is our new Avogadro's number according to the given conditions.Then, 1 atomic mass unit =1NA=26.023×1023Mass of 1 mole of O2=32× Avogrado's number ×26.023×1023=32×6.023×10232×26.023×1023=32gTherefore, there is no change in the mass number of O2.Hence, the correct option is (C).