Among the elements of the 3rd period from Na to Ar, pick out the element: (c). that is most reactive non-metal.

( a) no. Of electrons in atom of "A " will be only 12 as they are in third period and must have 3 shells and no. Of electrons in...

(a). Ar has highest first ionization enthalpy.

(b). Na has large atomic radius (covalent radius).

(d). Na is most reactive metal in third period. 

In group 1 elements (alkali metals) the reactivity of the metals is mainly due to the electron releasing tendency of their atoms, which is related to ionization enthalpy, Since ionization,...

(a) Fluorine is the most reactive among all halogens. However the reactivity deceases from F2 to I2 (from top to bottom of group) may be attributed to  (1) Low dissociation enthalpies  (2)...

Metal, because metal oxides are basic in nature.

It will be 7 in X as well as in Z The reason being that number of electrons in the outermost shell in the elements in same group is same.

Since the information given in the question is inaccurate, full marks are to be awarded to every candidate.