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 does which of the following?

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

2. It reduces permanganate to Mn²⁺

3. It oxidises oxalic acid to carbon dioxide and water

4. It gets oxidised by oxalic acid to chlorine

Find the metal used for coating iron during the process of galvanization.

Given 
\(\mathrm{E}_{\mathrm{Cr}^{3+} / \mathrm{Cr}}^0=-0.74 \mathrm{~V} ; \mathrm{E}_{\mathrm{MnO}_4^{-} / \mathrm{Mn}^{2+}}^0=1.51 \mathrm{V}\\{E}_{\mathrm{Cr}_2 \mathrm{O}_7^{2-} / \mathrm{Cr}^{3+}}^0=1.33 \mathrm{~V} ; \mathrm{E}_{\mathrm{Cl}_2 / \mathrm{Cl}^{-}}^0=1.36 \mathrm{~V}\)

Based on the data given above, strongest oxidizing agent will be:

Consider the following reaction :
\(a\mathrm{Cu}+b\mathrm{HNO}_{3} \rightarrow c\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}+d\mathrm{NO}+e\mathrm{H}_{2} \mathrm{O}\)
The values of a, b, and e in the reaction are, respectively:
1. 3, 8 and 4
2. 5, 2 and 8
3. 5, 2 and 16
4. 2, 5 and 8

Which of the following reactions is an example of a redox reaction?

1.  \(XeF_6+H_2O~\longrightarrow~XeOF_4+2HF\)
2.  \(XeF_6+2H_2O~\longrightarrow~XeO_2F_2+4HF\)
3.  \(XeF_4+O_2F_2~\longrightarrow~XeF_6+O_2\)
4.  \(XeF_2+PF_5~\longrightarrow~[XeF]^{+1}+PF_6~^-\)

Which of the following is the strongest reducing agent?

[Given: \(E_{Cl_{2}/Cl^{-}}^{o} = 1.36 V\); \(E_{Cr^{3+}/Cr}^{o} = -0.74 V\); 
\(E_{Cr_20_7^{2-}/Cr^{3+}}^{o} = 1.33 V\) and \(E_{MnO_4^{-}/Mn^{2+}}^{o} = 1.51 V\)]

The reaction of sulphur in an alkaline medium is given below:

${\mathrm{S}}_{8\left(\text{\hspace{0.17em}s}\right)}+{{\mathrm{aOH}}^{-}}_{\left(\mathrm{aq}\right)}\to {{\mathrm{bS}}^{2-}}_{(\mathrm{aq})}+{\mathrm{cS}}_2{{\mathrm{O}}_3^{2-}}_{\text{(aq)\hspace{0.17em}}}+{\mathrm{dH}}_2{\mathrm{O}}_{\left(\mathrm{\ell }\right)}$

The value of 'a' is: 

Calculate the percentage purity of H₂O₂ in a 0.200 g impure sample whose 20.0 mL solution reacts completely with 0.316 g of KMnO₄ in an acidic medium.

Given: Molar mass of H₂O₂ = 34 g mol⁻¹; molar mass of KMnO₄ = 158 g mol⁻¹.

1. 80
2. 85
3. 90
4. 92

The oxidation states of transition metal atoms in K₂Cr₂O₇, KMnO₄ and K₂FeO₄, respectively, are x, y and z.
The sum of x, y and z is:

1. 16

2. 12

3. 19

4. 22

The oxidation states of iron atoms in compounds (A), (B) and (C), respectively, are x, y and z. The sum of x, y and z is________.

Na₄[Fe(CN)₅NOS]         Na₄[FeO₄]       [Fe₂(CO)₉]

           (A)                         (B)                   (C)

1. 4  

2. 5

3. 6

4. 7