Conversion of PbSO₄ to Pbs is:

(1) reduction of S

(2) oxidation of S

(3) dissociation

(4) none of these

Oxidation number of Fe in K₃[Fe(CN)₆] is:

(a) +2

(b) +3

(c) +4

(d) +1

The correct order of reducing power of halide ions is:

(1) Cl^- > Br^- > I^- > F^-

(2) Cl^- >  I^- > Br^- > F^-

(3)  Br^- > Cl^- > I^- > F^-

(4)  I^- > Br^- > Cl^- > F^-

In which of the following processes nitrogen is oxidised?

(a) N${\mathrm{H}}_4^{+}$ $\to$N₂

(b) N${\mathrm{O}}_3^{-} \to$NO

(c) NO₂ $\to$N${\mathrm{O}}_2^{-}$

(d) NO₃ $\to$N${\mathrm{H}}_4^{+}$ 

Fluorine is a strong oxidising agent because:

(1) it has several isotopes

(2) it is very small and has 7 electrons in valency shell

(3) its valency is one

(4) it is the first member of the halogen series

The oxidation state of Ni in Ni(CO)₄ is:

(a) zero

(b) +4

(c) +8 

(d) +2

When SO₂ is passed through acidified solution of potassium dichromate, then chromium sulphate is formed. The change in oxidation number of chromium is:

(1) +4 to+2 

(2) +5 to+3

(3) +6 to+3

(4) +7 to+2

In the reaction;

2Ag + 2H₂SO₄ $\to$Ag₂SO₄ + 2H₂O + SO₂,H₂SO₄ acts as:

(1) oxidising agent

(2) reducing agent

(3) dehydrating agent

(4) none of these

In the equation,

N${\mathrm{O}}_2^{-}$ +  H₂O $\to$N${\mathrm{O}}_3^{-}$ + 2H⁺ + ne^-

n stands for:

(a) H⁺

(b) e^-

(c) 2e^-

(d) 3e^-

In the reaction between acidified K₂Cr₂O₇ and iron (II) ions shown by the equation:

Cr₂${\mathrm{O}}_7^{2-}$(aq) + 6Fe²⁺(aq) +14H⁺(aq)$\to$2Cr³⁺(aq) + 7H₂O(l) + 6Fe³⁺(aq)

(a) the colour of the solution changes from green to blue

(b) the iron (II) ions are reduced 

(c) the dichromate ions are reduced 

(d) hydrogen ions are reduced