Who introduced planatary model ​

Who introduced planetary model?

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Planetary model of the atom or Rutherford model or Rutherford atomic model or nuclear atom was proposed by Ernest Rutherford in 1911.

7is b8 is d9 is c10 is a11 is d

Answer : option a) 84explanation :

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.