Question

According to the image, identify the number of neutrons in the most common isotope of aluminum.

A) 13
B) 14
C) 26
D) 27

Answer 1

The number of neutron in the Aluminium Isotope is :

B. 14

Step-by-step explanation:

Isotopes : These are the atoms which have same atomic number but have different mass number.

This image shows the average atomic mass of Al element because it is in decimals.

Atomic mass = 26.98154

(Note : mass number of single isotope can never be in decimals)

It is the average of mass of different isotopes of Al

Major Isotopes of
`_(13)^(26.98154)\textrm{Al}` are :

1. 
   `_(13)^(26)\textrm{Al}`......atomic mass = 26
2. 
   `_(13)^(27)\textrm{Al}`.......atomic mass = 27

mass of Al given in image(26.98) is nearly equal to mass of 2nd isotope(27)

mass of
`_(13)^(26.98154)\textrm{Al}\ \approx 27`

Now calculate the neutron in
`_(13)^(27)\textrm{Al}`

Number of neutron = mass number - atomic number

= 27 - 13

Number of neutron = 14

(Atomic mass is same as mass number)