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An element with mass number 81 contains ...

An element with mass number `81` contains `31.7%` more neutrons as compared to protons. Write the symbol for the isotope in the standard fromat.
Strategy: Let us assume that the number of protons `=p`. Then, Number of neutrons `(n) = p +31.7%`of `p`

Text Solution

Verified by Experts

Mass number `=` Number of protons `+` Number of neutrons
`81=p +n`
or `p+(p+(31.7)/(100)xxp)=81`
`p+(p +0.317p) = 81`
`p+p(1+0.317) = 81`
`p+1.317p = 81`
`(1+1.317)p = 81`
`2.317 p = 81`
`p = (81)/(2.317) 34.95~= 35`
According to the periodic table, the element with atomic number `35` is bromine, Br. Therefore, the symbol is `_(35)^(81)Br`.
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Knowledge Check

  • An element with mass number 81 contains 31.7% more neutrons as compared to protons. Assign the atomic symbol.

    A
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    B
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  • Species X with mass number 37 contains 11.1 % more neutrons as compared to electrons , then what is the incorrect repesentation of element x?

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  • A hypothetical of element X with mass number 40, posses 2 units of positive charge and 23% more neutrons than electrons. Symbol of the ion is :

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