Which is incorrect configuration for s-block elements?
A.$\left[ {Ar} \right]3{d^{10}}4{s^2}$
B.$\left[ {Ar} \right]3{d^{10}}4{s^1}$
C. Both A and B
D. None of these

Hint: The s-block elements have one or two electrons in their outermost s-orbitals preceded by the noble gas configuration. They contain alkali and alkaline earth metals.

Complete step by step answer:
The s-block elements have electronic configuration-$\left[ {{\text{Noble gas}}} \right]n{s^{1 - 2}}$ where n is the valence shell. The alkali earth metals have one electron in their outermost s-orbital while the alkaline earth metals have two electrons in their outermost s-orbital. They are the most reactive elements of all the metals. They are not found in the free State in nature. They are found in combined forms with halide, oxide, sulphate, carbonate or silicate.
Here in option A, the electron is filled in d-orbital after s-orbital so it is d-block element configuration.
And in option B also, the electron is filled in d-orbital after s-orbital so it is not a s-block element but a d-block element.
So both the configurations are incorrect for s-block elements.

Hence the correct answer is C.

Additional Information
-The s-block contains $14$ elements and their properties are-
-They are soft metals possessing low melting and boiling point.
-They are good conductors of heat and electricity.
-They are highly electropositive as they have very low ionization enthalpy.
-They form ionic compounds easily. Except for Beryllium and magnesium, they impart colour to the flame.
-They are strong reducing agents

Note:
The uses of s-block elements are-
-Lithium is used to create alloys with other metals which are used to make armour plates, aeroplanes, motor engines and sheets for cables.
-Cesium is used to make photoelectric cells.
-Potassium is used to make fertilizers.
-Beryllium is also used for creating alloys.
-Sodium in its liquid state is used as a coolant infirm breeder for nuclear reactors.
-Radium is used in radiotherapy.