Redox Reactions · JEE Main previous year questions

2002 4 questions

1. Q1812002 · 27 Apr 2002 · Shift 1

   Which of the following is a redox reaction ?

   1. A.$\mathrm{NaCl}+\mathrm{KN}{\mathrm{O}}_3\to \mathrm{NaN}{\mathrm{O}}_3+\mathrm{KCl}$
   2. B.$\mathrm{Ca}{\mathrm{C}}_2{\mathrm{O}}_4+2HCl\to \mathrm{CaC}{\mathrm{l}}_2+{\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4$
   3. C.$\mathrm{Mg}(\mathrm{OH}{)}_2+2N{\mathrm{H}}_4\mathrm{Cl}\to \mathrm{MgC}{\mathrm{l}}_2+2N{\mathrm{H}}_4\mathrm{OH}$
   4. D.$\mathrm{Zn}+2AgCN\to 2Ag+\mathrm{Zn}(\mathrm{CN}{)}_2$
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   Answer: D

2. Q1892002 · 27 Apr 2002 · Shift 1

   Oxidation number of Cl in $\mathrm{CaOC}{\mathrm{l}}_2$ (bleaching powder) is :

   1. A.zero, since it contains $\mathrm{C}{\mathrm{l}}_2$
   2. B.-1, since it contains $\mathrm{C}{\mathrm{l}}^{-}$
   3. C.+1, since it contains $\mathrm{Cl}{\mathrm{O}}^{-}$
   4. D.+1 and -1 since it contains $\mathrm{Cl}{\mathrm{O}}^{-}$ and $\mathrm{C}{\mathrm{l}}^{-}$
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   Answer: D

3. Q1902002 · 27 Apr 2002 · Shift 1

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

   1. A.4, 3, 1, 5
   2. B.1, 5, 3, 7
   3. C.1, 3, 4, 5
   4. D.3, 5, 7, 1
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   Answer: C

4. Q1922002 · 27 Apr 2002 · Shift 1

   Most common oxidation states of Ce (cerium) are :

   1. A.+3, +4
   2. B.+2, +3
   3. C.+2, +4
   4. D.+3, +5
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   Answer: A