25.0 g of FeSO₄.7H₂O was dissolved in water containing dilute H₂SO₄, and the volume was made up to 1.0 L. 25.0 mL of this solution required 20 mL of an N/10 KMnO₄ solution for complete oxidation. The percentage of FeSO₄^. 7H₂O in the acid solution is

(1) 78%

(2) 98%

(3) 89%

(4) 79%

Which one of the following orders correctly represents the increasing acid strengths of the given acids?

(1) HOCl<HOClO<HOClO₂<HOClO₃

(2) HOClO<HOCl<HOClO₃<HOClO₂

(3) HOClO₂<HOClO₃<HOClO<HOCl

(4) HOClO₃>HOClO₂<HOClO<HOCl

The valency of Cr in the complex [Cr(H₂O)₄Cl₂]⁺ [MP PMT 2000]

(1) 1

(2) 3

(3) 5

(4) 6

Oxidation number of cobalt in K[Co(CO)₄] is

(1) + 1

(2) + 3

(3) – 1

(4) – 3

The oxidation number of phosphorus in Ba(H₂PO₂)₂ is [Kurukshetra CEE 1998; DCE 2004]

(1) – 1

(2) + 1

(3) + 2

(4) + 3

When KMnO₄ acts as an oxidising agent and ultimately forms ${\left[Mn{O}_4\right]}^{-2},Mn{O}_2,M{n}_2{O}_3,M{n}^{+2}$ then the number of electrons transferred in each case respectively is [AIEEE 2002]

(1) 4, 3, 1, 5

(2) 1, 5, 3, 7

(3) 1, 3, 4, 5

(4) 3, 5, 7, 1

For the redox reaction $Mn{O}_4^{-}+C_2{O}_4^{-2}+H^{+}\to M{n}^{2+}+C{O}_2+H_{2}O$ 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]

Which of the following is the strongest oxidising agent [Pb. CET 2000]

(1) $Br{O}_3^{-}/B{r}^{2+},E^o=+1.50$

(2) $F{e}^{3+}/F{e}^{2+},E^o=+0.76$

(3) $Mn{O}_4^{-}/M{n}^{2+},E^o=+1.52$

(4) $C{r}_2{O}_7^{2-}/C{r}^{3+},E^o=+1.33$

Oxidation number of oxygen in potassium super oxide (KO₂) is [UPSEAT 1999, 2002]

(1) – 2

(2) – 1

(3) – 1/2

(4) – 1/4

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