If 10 gm of V_{2}O_{5} is dissolved in acid and is reduced to V^{2+} by zinc metal, how many mole of I_{2} could be reduced by the resulting solution if it is further oxidised to VO^{2+ }ions ? [Assume no change in state of Zn^{2}+ions] (V = 51, O =16, I = 127) :
(1) 0.11 mole of I_{2}
(2) 0.22 mole of I_{2}
(3) 0.055 mole of I_{2}
(4) 0.44 mole of I_{2}
Difficulty Level:
Oxidation numbers of P in ${\mathrm{PO}}_{4}^{3}$, of S in ${\mathrm{SO}}_{4}^{2}$ and that of Cr in ${\mathrm{Cr}}_{2}{\mathrm{O}}_{7}^{2}$ are respectively,
(a) +5, +6 and +6 (b) +3, +6 and +5
(c) +5, +3 and +6 (d) 3, +6 and +6
Difficulty Level:
The number of mole of KMnO_{4} that will be needed to react with one mole of sulphite ion in acidic solution is:
(a) $\frac{3}{5}$
(b) $\frac{4}{5}$
(c) $\frac{2}{5}$
(d) 1
Difficulty Level:
For the redox reaction $Mn{O}_{4}^{}+{C}_{2}{O}_{4}^{2}+{H}^{+}\to \text{\hspace{0.17em}}M{n}^{2+}+C{O}_{2}+{H}_{2}O$ the correct coefficients of the reactants for the balanced reaction are [IIT 1988, 92; BHU 1995; CPMT 1997; RPMT 1999; DCE 2000; MP PET 2003]

$Mn{O}_{4}^{}$ 
${C}_{2}{O}_{4}^{2}$ 
${H}^{+}$ 
(1) 
2 
5 
16 
(2) 
16 
5 
2 
(3) 
5 
16 
2 
(4) 
2 
16 
5 
Difficulty Level:
The number of moles of KMnO_{4} reduced by one mole of KI in alkaline medium is: [CBSE PMT 2005]
(1) One fifth
(2) five
(3) One
(4) Two
Difficulty Level:
The compound ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$ which shows superconductivity has copper in oxidation state ........ Assume that the rare earth element Yttrium is in its usual +3 oxidation state [IIT 1994]
(1) 3/7
(2) 7/3
(3) 3
(4) 7
Difficulty Level:
In a balanced equation ${H}_{2}S{O}_{4}+x\text{\hspace{0.17em}}HI\to {H}_{2}S+y\text{\hspace{0.17em}}{I}_{2}+z\text{\hspace{0.17em}}{H}_{2}O$, the values of x, y, z are [EAMCET 2003]
(1) x = 3, y = 5, z = 2
(2) x = 4, y = 8, z = 5
(3) x = 8, y = 4, z = 4
(4) x = 5, y = 3, z = 4
Difficulty Level: