question_answer 61)

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

Answer:

Let number of protons in the element = \[x\] Number of neutrons = \[\frac{131.7}{100}x=1.317x\] Mass number = \[x+1.317x\] \[81=2.317x\] \[x=34.95=35\] Atomic symbol will be ( \[\,_{35}^{81}Br\]).