Amount of oxalic acid present in a solution can be determined by its titration with KMnO₄ solution in the presence of H₂SO₄. The titration gives unsatisfactory result when carried out in the presence of HCl, because HCl:

1. oxidises oxalic acid to carbon dioxide and water

2. gets oxidised by oxalic acid to chlorine

3. furnishes H⁺ ions in addition to those from oxalic acid

4. reduces permanganate to Mn²⁺

KMnO₄ in acidic medium is always reduced to:

1. Mn⁴⁺ 

2. Mn²⁺ 

3. Mn⁶⁺

4. Mn

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)

The correct statement among the following is -

1. Colour of the solution changes from green to blue

2. Iron (II) ions are reduced 

3. Dichromate ions are reduced 

4. Hydrogen ions are reduced

The oxidation number of carbon in C₃O₂  and Mg₂C₃ are respectively:

1. -4/3, +4/3 

2. +4/3, -4/3

3. -2/3, +2/3

4. -2/3, +4/3

Which metal exhibits more than one oxidation states?

1. Na

2. Mg

3. Al

4. Fe

The decomposition of KClO₃ to KCl and O₂ on heating is an example of:

1. intermolecular redox change

2. intramolecular redox change

3. disproportionation or auto redox change

4. none of the above

Among the following, In which iron has the lowest oxidation state?

1. Fe(CO)₅

2. Fe₂O

3. K₄Fe(CN)₆

4. FeSO₄.(NH₄)₂SO₄.6H₂O

Reducing agent among the following is -

The equivalent mass of a reductant or an oxidant is given by:

1. Eq. mass = $\frac{molar mass of reduc\tan t or oxidant}{no. of electrons lost or gained by 1 molecule of reduc\tan t or oxidant}$

2. Eq. mass = $\frac{molar mass}{valence}$

3. Eq. mass = $\frac{molar mass}{total charge on cation or anion}$$$

4. All of the above

NaH+ H₂O $\to$NaOH + H₂:

The correct statement for above mentioned reaction among the following is-

1. H^- is oxidised

2. Na⁺ is reduced

3. Both NaH and H₂O are reduced 

4. None of the above