Question

Q18) An element with mass number 81 contains 31.7% more neutrons as compared to protons. Assign the atomic symbol.

Answer 1

HEYA.

Number of protons +Number of neutrons = mass number = 81
Let the number of protons = x
Number of neutrons = x131.7/100 = 1.317x
X+1.317x = 81
X = 35
So, atomic number = 35
Element with atomic number 35 =Br


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Answer 2

Hey mate!

Here's your answer!!

We know that mass number of the element,
A = p+n = 81
Let the number of protons, p = x

Then, number of neutrons,
n = x + 31.7 / 100x = 1.317 x

(As number of neutrons are 31.7% more than the protons.)

Hence, from Eq. (i)
x + 1.317 x = 81
x = 81 / 2.317 = 34.958 = 35 (approx)

Therefore, number of protons = 35 and the symbol is {35}^{81}Br
(Number of protons = Atomic number)

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