An ion (M2+) contain 10 electrons and 12 neutrons what is the atomic number and mass number of the element M.

Since, M2+ contains 10 electrons and  the M2+ ion suggests that it has lost 2 electrons so it contains total 12 electrons. The number of electrons are equal to number of protons in an atom, so its atomic number is 12.

The no of protons and neurones is known as  mass number which is 24 (12 + 12 = 24.)


  • 15
  • atomic no. = 10[ atomic no. is the number of protons or electrons]
  • mass no.= 10+12=22 u[ sum of electrons or protons and neutrons]
  • -2
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