Question

A, B and C are hydroxy-compounds of the elements X, Y and Z respectively. X, Y and Z are in the same period of the periodic table. A gives an aqueous solution of pH less than seven. B reacts with both strong acids and strong alkalis. C gives an aqueous solution which is strongly alkaline

Which of the following statements is/are true

I : The three elements are metals

II : The electronegativities decrease from X to Y to Z.

III : The atomic radius decreases in the order X, Y and Z.

IV : X, Y and Z could be phosphorus, aluminium and sodium respectively :

• A. I, II, III only correct
• B. I, III only correct
• C. II, IV only correct
• D. II, III, IV only correct

Answer 1

The correct option is C II, IV only correct

X, Y, Z

$X\to$ pH less than 7 the hydroxyl compound should be an acid to give pH less than 7.

$Y\to$ If it reacts with both acids and bases, the oxide of metal should be amphoteric

$Z\to$ To be strongly alkaline it should be metal of group 1 or 2

$\left(X\right)P\to$ forms hydroxide which is acid

$\left(Y\right)Al\to$ forms hydroxide reacts with both acids and bases.

$\left(Z\right)Na\to$ forms hydroxide reacts with strongly alkaline.

Atomic radius increases from X to Z

$X<Y<Z$

Electronegativity $Z<Y<X$.