In which pair of ions both the species contain S-S bond?

 

1. ${\mathrm{S}}_4{\mathrm{O}}_6^{2-}, {\mathrm{S}}_2{\mathrm{O}}_3^{2-}$

 

2. ${\mathrm{S}}_2{\mathrm{O}}_7^{2-}, {\mathrm{S}}_2{\mathrm{O}}_8^{2-}$

 

3. ${\mathrm{S}}_4{\mathrm{O}}_6^{2-}, {\mathrm{S}}_2{\mathrm{O}}_7^{2-}$

 

4. ${\mathrm{S}}_2{\mathrm{O}}_7^{2-}, {\mathrm{S}}_2{\mathrm{O}}_3^{2-}$

 

Hot concentrated sulphuric acid is a moderately strong oxidizing agent. Which of the following reaction does not show - ­oxidising behaviour?

1.  $\mathrm{Cu}+2{\mathrm{H}}_2{\mathrm{SO}}_4 \to {\mathrm{CuSO}}_4+{\mathrm{SO}}_2+2{\mathrm{H}}_2\mathrm{O}$

2.  $3\mathrm{S}+2 {\mathrm{H}}_2{\mathrm{SO}}_4 \to 3{\mathrm{SO}}_2+2{\mathrm{H}}_2\mathrm{O}$

3.  $\mathrm{C}+2\mathrm{H}2{\mathrm{SO}}_4 \to {\mathrm{CO}}_2+2{\mathrm{SO}}_2+2{\mathrm{H}}_2\mathrm{O}$

4.  ${\mathrm{CaF}}_2+{\mathrm{H}}_2{\mathrm{SO}}_4 \to {\mathrm{CaSO}}_4+2\mathrm{HF}$

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

Roasting of sulphides gives the gas 'X' as a by-product. This is a colourless gas with the choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic, acts as an oxidising agent, and its acid has never been isolated. The gas 'X' is:

1. SO₂

2. CO₂

3. SO₃

4. H₂S

Which of the following statements is not valid for oxoacids of phosphorus?

1. Orthophosphoric acid is used in the manufacture of triple  superphosphate

2. Hypoposhphorous acid is a diprotic acid

3. All oxoacids contain tetrahedral four coordinated phosphorus

4. All oxoacids contain at least one P=O unit and one P-OH group

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