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Question
An element with mass number 81 contains 31.7% more neutrons as compared to protons. Assign the atomic symbol.
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Solution
Let the number of protons in the element be x.
∴ Number of neutrons in the element
= x + 31.7% of x
= x + 0.317 x
= 1.317 x
According to the question,
Mass number of the element = 81
∴ (Number of protons + number of neutrons) = 81
`=> x + 1.317x = 81`
`2.317x = 81`
`x = 81/2.317`
= 34.95
`therefore x = 35`
Hence, the number of protons in the element i.e., x is 35.
Since the atomic number of an atom is defined as the number of protons present in its nucleus, the atomic number of the given element is 35.
∴ The atomic symbol of the element is `""_35^81"Br"`
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