Question

Which of the following atoms does the electron configuration $1s^2,2s^2,2p^6,3s^2,3p^6,3d^2$ represent?

• A. An excited $Ca$ atom
• B. A neutral $Ca$ atom
• C. An excited $Sc$ atom
• D. An excited $K$ atom

Answer 1

The correct option is A An excited $Ca$ atom

The total number of electrons in the mentioned element is $2+2+6+2+6+2=20$ i.e., the element has an atomic number $20$, i.e., the element is Calcium (Ca).

However the neutral $Ca$ atom has configuration $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^2$. Thus the atom mentioned in question is excited state of $Ca$.