Question

How many neurons does elements X have if’s atomic number is 21 and its mass number is 76

Answer 1

The element has 55 neutrons.

Step-by-step explanation:

mass number= A= 76

atomic number= Z= 21

Mass number is the sum of number of protons and neutrons present in a nucleus while as the atomic number is the number of protons present in a nucleus.

so the number of neutrons= Mass number- Atomic number

n= A-Z

n=76-21

n= 55