Question

For Fe, its atomic number is 26 and its mass number is 56. How many neutrons does it have? a.26 b.30 c.56 d.82

Answer 1

Iron (Fe) has "30" nuetrons. 

Answer 2

Answer : The correct option is, (b) 30

Explanation :

Atomic number : It is defined as the number of protons or number of electrons.

Atomic number = number of protons = number of electrons

Mass number : It is defined as the sum of number of protons and number of neutrons.

Mass number = Number of protons  + Number of neutrons

As we are given that,

Atomic number = 26

Mass number = 56

As we know that:

Atomic number = Number of protons = 26

Mass number = Number of protons  + Number of neutrons

or,

Number of neutrons = Mass number - Number of protons

Number of neutrons = 56 - 26

Number of neutrons = 30

Thus, the number of neutrons in Fe are, 30