Which item completes the electron configuration of Sodium (Na)?

$$1s^2$$ $$2s^2$$ (a)   $$3s^1$$

Which item completes the electron configuration of Chlorine (Cl)?

$$1s^2$$ $$2s^2$$ $$2p^6$$ (a)   $$3p^5$$

Which is the last electron configuration (LEC) of Magnesium (Mg)?

$$1s^2$$ $$2s^2$$ $$2p^6$$ (a)  

Which is the last electron configuration (LEC) of Argon (Ar)?

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ (a)  

Which element is described in the electron configuration below? Give its chemical name.

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^3$$

(a)  

Which element is described in the electron configuration below? Give its chemical name.

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$

(a)  

Which element is described in the electron configuration below? Give its chemical name.

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$ $$3d^6$$

(a)  

Which element is described in the electron configuration below? Give its chemical symbol.

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$ $$3d^{10}$$ $$4p^6$$ $$5s^2$$ $$4d^{10}$$ $$5p^5$$

(a)  

Which element is described in the electron configuration below? Give its chemical symbol.

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$ $$3d^{10}$$ $$4p^6$$ $$5s^2$$ $$4d^{10}$$ $$5p^6$$ $$6s^2$$ $$4f^7$$

(a)