Identify the incorrect statement regarding the halogens.

1. All form monobasic oxyacids.
2. All are oxidizing agents.
3. All but fluorine show positive oxidation states.
4. Chlorine has the highest electron-gain enthalpy.

In the structure of ClF₃, the number of lone pairs of electrons on central atom 'Cl' is:

1. 1

2. 2

3. 3

4. 4

Match the compounds given in Column I with the  shape given in Column II and mark the correct option. 

Which of the statements given below is incorrect?

1. $C{l}_2{O}_{7 }$is an anhydride of perchloric acid

2. $O_3$ molecule is bent

3. ONF is isoelectronic with $N{O}_2^{-}$

4. $O{F}_2$ is an oxide of fluorine

The variation of the boiling point of the hydrogen halides is in the order HF > HI > HBr > HCl. 
The higher boiling point of hydrogen fluoride is explained as:

The strong reducing behaviour of H₃PO₂ is due to:

1. Presence of one -OH group and two P-H bonds.

2. High electron gain enthalpy of phosphorus.

3. High oxidation state of phosphorus.

4. Presence of two -OH groups and one P-H bond.

The acidity of diprotic acids in aqueous solution increases in the order:

1. H₂S < H₂Se < H₂Te

2. H₂Se < H₂S < H₂Te

3. H₂Te < H₂S < H₂Se

4. H₂Se < H₂Te < H₂S

Which of the following compounds does not release oxygen when heated?

1. Zn(ClO₃)₂
2. K₂Cr₂O₇
3. (NH₄)₂Cr₂O₇
4. KClO₃