# In an atom the number of electrons in M-shell is equal to the number of electrons in the K and L shell

In an atom the number of electrons in M-shell is equal to the number of electrons in the K and L shell. Answer the following questions.
a) Which is the outermost shell ?
b) How many electrons are there in its outermost shell ?
c) What is the atomic number of element ?
d) Write the electronic configuration of the element.

No. of electrons in â€˜Mâ€™ shell is equal to number of electrons in the K and L shells. .-. No. of electrons in M shell = 2 + 8 = 10 Total electrons in the given atom = 2(K) + 8(L) + 10(M) = 20 The electronic configuration : \${{1s}^{2}}\$ \${{2s}^{2}}\$ \${{2p}^{6}}\$ \${{3s}^{2}}\$ \${{3p}^{6}}\$ \${{4s}^{2}}\$ \${{3d}^{2}}\$
a) M shell is the outermost shell.
b) There are â€˜2â€™ electrons in the outer most shell.
c) The atomic number of the element is 20.
d) Electronic configuration of the element: \${{1s}^{2}}\$ \${{2s}^{2}}\$ \${{2p}^{6}}\$ \${{3s}^{2}}\$ \${{3p}^{6}}\$ \${{4s}^{2}}\$