Which of the statements given below is incorrect?

1. \(\mathrm{C l_{2} O_{7  }}\)${}_{}$is an anhydride of perchloric acid
2. \(\mathrm{O_{3}}\)${\mathrm{}}_{}$ molecule is bent
3. ONF is isoelectronic with \(\mathrm{N O_{2}^{-}}\)${}_{}^{}$ 
4. \(\mathrm{O F_{2}}\) is an oxide of fluorine

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

Sulphur trioxide can be obtained by which of the following reaction:

1. $CaS{O}_4+C\stackrel{∆}{\to }$

2. $F{e}_2(S{O}_4{)}_3\stackrel{∆}{\to }$

3. $S+H_{2}S{O}_4\stackrel{∆}{\to }$

4. $H_{2}S{O}_4+PC{l}_5\stackrel{∆}{\to }$

The given sequence among the following arrangements that is not strictly according to the property indicated against it.  

Match List-I (substances) with List-II (processes) employed in the manufacture of the substances and select the correct option.