Which of the following acids forms three series of salts?

1

(a)

H₃PO₂

(b)

H₃BO₃

(c)

H₃PO₄

(d)

H₃PO₃

Strong reducing behaviour of H₃PO₂ is due to

1

(a)

Low oxidation state of phosphorus

(b)

Presence of two -OH groups and one P-H

(c)

Presence of One -OH group and two P-H bonds

(d)

High electron gain enthalpy of phosphorus.

On heating, lead nitrate forms oxides of nitrogen and lead. The oxides formed are.......

1

(a)

N₂O, PbO

(b)

NO₂ ,PbO

(c)

NO, PbO

(d)

NO, PbO₂

Which of the following elements does not show allotropy?

1

(a)

Nitrogen

(b)

Bismuth

(c)

Antimony

(d)

Arsenic

Maximum covalency of nitrogen is.....

1

(a)

3

(b)

5

(c)

4

(d)

6