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

Q- 2.42 An element with mass number 81 contains 31.7% more neutrons as compared to protons. Assign the atomic symbol.
Answer
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

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