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An element with a mass number of 81 contains 31.7% more neutrons as compared to protons. Identify the element

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answer is C.

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Detailed Solution

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 element is Br.

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