Question

all element has atomic number 8 contain same neutrons as protons tell its at mass​

Answer 1

Let x be the number of protons.  

The number of neutrons is x+0.317x=1.317x.  

The mass number is 81.  

It is equal to the sum of the number of protons and the number of neutrons.

81=x+1.317x=2.317x

x=35

Hence, the symbol is  

35

81

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