Redox reaction among the following is -

1. NaCl + KNO₃ $\to$NaNO₃ + KCl

2. CaC₂O₄ + 2HCl $\to$CaCl₂ + H₂C₂O₄

3. Mg(OH)₂ + 2NH₄Cl $\to$MgCl₂ + 2NH₄OH

4. Zn + 2AgCN $\to$2Ag + Zn(CN)₂

The oxidation number of Fe in K₃[Fe(CN)₆] is-

1. +2

2. +3

3. +4

4. +1

It is found that v forms a double salt isomorphous with Mohr's salt. The oxidation number of V in this compound is:

1. +3

2. +2

3. +4

4. -4

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^-

The reaction during which nitrogen gets oxidised is-

1. ${\mathrm{NH}}_4^{+}$ $\to$N₂

2. ${\mathrm{NO}}_3^{-} \to$NO

3. NO₂ $\to$${\mathrm{NO}}_2^{-}$

4. ${\mathrm{NO}}_3^{-}$$\to$N${\mathrm{H}}_4^{+}$ 

Reaction that shows hydrogen as an oxidising agent is:

1. With iodine to give hydrogen iodide

2. With lithium to give lithium hydride

3. With nitrogen to give ammonia

4. With sulphur to give hydrogen sulphide

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:

1. zero

2. +4

3. +8 

4. +2

Sulphurous acid can be used as:

1. Oxidising agent

2. Reducing agent

3. Bleaching agent

4. All of the above

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