NCERT Class XI Chemistry Structure of Atom Solutions

Question : 42

Total: 67

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

Solution:

We know that A = p + n ⇒ 81 = p + n
Let number of protons = x
According to question,
No. of neutrons = x +

x×31.7

100

= 1.317 ∴ x + 1.317x = 81 or 2.317x = 81
∴ x =

2.317

= 34.96 ≈ 35.
Thus , symbol =

‌

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