Question

Three elements X, Y and Z are in the 3^rd period of the periodic table. The oxides of X, Y and Z, respectively, are basic, amphoteric and acidic. The correct order of the atomic numbers of X, Y and Z is:

(1) X < Y < Z 

(2) Z < Y < X 

(3) X < Z < Y 

(4) Y < X < Z

Answer 1

Ans. (1) X < Y < Z

Sol. On moving left to right in a period.

Acidic character of oxides is increase.

3^rd period element oxides.

$\underbrace{Na_2O\ MgO}_{Basic}\underbrace{Al_2O_3}_{Amphoteric}\underbrace{SiO_2\ P_2O_5\ Cl_2O_7}_{Acidic}$

(i) Acidic character $\uparrow$

(ii) Atomic No $\uparrow$

So X have minimum Atomic No & Z have maxima Atomic No

So correct order is X < Y < Z

Comments

Over here, since X has the highest atomic number, it should be X>Y>Z or Z<Y<X.