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 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: 

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

The strongest reducing agent among the following is:

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.   \(XeF_2+PF_5~\longrightarrow~[XeF]^{+1}+PF_6~^-\)

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

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 - 

1. Mn²⁺

2. $Mn{O}_4^{-}$

3. Cl^–

4. Cr³⁺

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

While titrating dilute HCl solution with aqueous NaOH, which of the following will not be required?
1.  Clamp and phenolphthalein
2.  Pipette and distilled water
3.  Burette and porcelain tile
4.  Bunsen burner and measuring cylinder

Given that: 

 \(\begin{aligned} &E_{\mathrm{O}_{2} / \mathrm{H}_{2} \mathrm{O}}^{\Theta}=+1.23 \mathrm{~V} ; E_{S_{2} \mathrm{O}_{8}^{2-} / \mathrm{{SO}_{4}}^{-2}}=2.05 \mathrm{~V} \\ &E_{\mathrm{Br}_{2} / \mathrm{Br}^{-}}^{\Theta}=+1.09 \mathrm{~V} ; E_{A u^{3+} / A u}^{\Theta}=+1.4 \mathrm{~V} \end{aligned}\)

Which of the following is the strongest oxidizing agent?
1. \(\mathrm{S}_2 \mathrm{O}_8^{2-}\) ${}_{}$

2. \(\mathrm{O}_2\) ${}_{}$

3. \(A u^{3+}\)$$

4. \(B r_2\)

Which of the following is a redox reaction? 

1. NaCl  + KNO₃ \(\rightarrow\) NaNO₃  + KCl

2. CaC₂O₄  + 2HCl  \(\rightarrow\)  CaCl₂ + H₂C₂O₄  

3. Ca(OH)₂  + 2NH₄Cl  \(\rightarrow\)  CaCl₂ + 2NH₃ + 2H₂O 

4. 2K[Ag(CN)₂]  + Zn  \(\rightarrow\)  2Ag + K₂[Zn(CN)₄]