
How many electrons are present in the M-shell of an element with atomic number 20?
A) 8
B) 6
C) 18
D) 2
Answer
438.7k+ views
1 likes
Hint: K-shell is the first energy level and can have a maximum of 2 electrons. L-shell is the Second energy level and can have a maximum of 8 electrons. M-shell is the third energy level and can have a maximum of 18 electrons.
Complete step by step answer:
In an atom, the electrons surround the nucleus in different orbitals or energy levels. These orbitals are known as either first, second, third ... energy levels or K,L,M, N... shells. K-shell is the first energy level and can have a maximum of 2 electrons. L-shell is the second energy level and can have a maximum of 8 electrons. M-shell is the third energy level and can have a maximum of 8 electrons.
The atomic number of an element is 20. Atomic number is equal to the number of electrons present in a neutral atom. Thus, the element with atomic number 20 has 20 electrons. Out of 20 electrons, 2 electrons are present in the K-shell and 8 electrons are present in the L-shell. Out of the remaining 20-(2+8)=10 electrons, 8 electrons are present in the M-shell and 2 electrons are present in the N shell.
Hence, 8 electrons are present in the M-shell of an element with atomic number 20.
The structure of atom is as shown below:
Thus, option A is the correct answer.
Additional information: The electronic configuration of the element with atomic number 20 is .
Note:
Do not put more than 2 electrons in K-shell and more than 8 electrons each in L and M-shells.
Complete step by step answer:
In an atom, the electrons surround the nucleus in different orbitals or energy levels. These orbitals are known as either first, second, third ... energy levels or K,L,M, N... shells. K-shell is the first energy level and can have a maximum of 2 electrons. L-shell is the second energy level and can have a maximum of 8 electrons. M-shell is the third energy level and can have a maximum of 8 electrons.
The atomic number of an element is 20. Atomic number is equal to the number of electrons present in a neutral atom. Thus, the element with atomic number 20 has 20 electrons. Out of 20 electrons, 2 electrons are present in the K-shell and 8 electrons are present in the L-shell. Out of the remaining 20-(2+8)=10 electrons, 8 electrons are present in the M-shell and 2 electrons are present in the N shell.
Hence, 8 electrons are present in the M-shell of an element with atomic number 20.
The structure of atom is as shown below:

Thus, option A is the correct answer.
Additional information: The electronic configuration of the element with atomic number 20 is
Note:
Do not put more than 2 electrons in K-shell and more than 8 electrons each in L and M-shells.
Latest Vedantu courses for you
Grade 11 Science PCM | CBSE | SCHOOL | English
CBSE (2025-26)
School Full course for CBSE students
₹41,848 per year
Recently Updated Pages
Master Class 11 Accountancy: Engaging Questions & Answers for Success

Master Class 11 Social Science: Engaging Questions & Answers for Success

Master Class 11 Economics: Engaging Questions & Answers for Success

Master Class 11 Physics: Engaging Questions & Answers for Success

Master Class 11 Biology: Engaging Questions & Answers for Success

Class 11 Question and Answer - Your Ultimate Solutions Guide

Trending doubts
Explain why it is said like that Mock drill is use class 11 social science CBSE

The non protein part of an enzyme is a A Prosthetic class 11 biology CBSE

Which of the following blood vessels in the circulatory class 11 biology CBSE

What is a zygomorphic flower Give example class 11 biology CBSE

1 ton equals to A 100 kg B 1000 kg C 10 kg D 10000 class 11 physics CBSE

The deoxygenated blood from the hind limbs of the frog class 11 biology CBSE
