. An element with mass number 81 contains

Best Answer

Explanation:

• The mass number of an element is the sum of its protons and neutrons.
• Let the number of protons of the element be x.
• The number of neutrons is 31.7% more than the number of protons.

Therefore, the number of neutrons is  x+0.317x=1.317x.

• The mass number of the element is 81.

1.317x + x=81

2.317x=81

x=35

• Therefore, the atomic number of this element= number of protons  = 35, which is Bromine.
• Therefore, the atomic symbol is  
• Final answer:

Correct Answer is