In an atom,if the $K$-shell has $2$ electrons,the $L$-shell has $8$ electrons,and the $M$-shell has $6$ electrons,what is the total number of electrons in the atom?

Explain $d$ orbital.

On what does the energy of hydrogen and hydrogen-like species depend? On what does it not depend?

For both $2p$ and $3s$ orbitals,the value of $(n + l)$ is equal to $3$. Which of these has lower energy and why?

As per the modern periodic law,the physical and chemical properties of elements are periodic functions of their

The electrons,identified by quantum numbers $n$ and $l$ as $(i) n = 4, l = 1$,$(ii) n = 4, l = 0$,$(iii) n = 3, l = 2$,$(iv) n = 3, l = 1$,can be placed in order of increasing energy,from the lowest to highest,as: