Chemical & Ionic Equilibrium · JEE Main previous year questions

2004 7 questions

1. Q1542004 · 24 Apr 2004 · Shift 1

   Among $\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3,\mathrm{Si}{\mathrm{O}}_2,{\mathrm{P}}_2{\mathrm{O}}_3$ and $\mathrm{S}{\mathrm{O}}_2$ the correct order of acid strength is

   1. A.$\mathrm{S}{\mathrm{O}}_2<{\mathrm{P}}_2{\mathrm{O}}_3<\mathrm{Si}{\mathrm{O}}_2<\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$
   2. B.$\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3<\mathrm{Si}{\mathrm{O}}_2<{\mathrm{P}}_2{\mathrm{O}}_3<\mathrm{S}{\mathrm{O}}_2$
   3. C.$\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3<\mathrm{Si}{\mathrm{O}}_2<\mathrm{S}{\mathrm{O}}_2<{\mathrm{P}}_2{\mathrm{O}}_3$
   4. D.$\mathrm{Si}{\mathrm{O}}_2<\mathrm{S}{\mathrm{O}}_2<\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3<{\mathrm{P}}_2{\mathrm{O}}_3$
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   Answer: B

2. Q1642004 · 24 Apr 2004 · Shift 1

   The conjugate base of ${\mathrm{H}}_2\mathrm{P}{\mathrm{O}}_4^{-}$ is :

   1. A.$\mathrm{P}{\mathrm{O}}_4^{3-}$
   2. B.$\mathrm{HP}{\mathrm{O}}_4^{2-}$
   3. C.${\mathrm{H}}_3\mathrm{P}{\mathrm{O}}_4$
   4. D.${\mathrm{P}}_2{\mathrm{O}}_5$
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   Answer: B

3. Q1652004 · 24 Apr 2004 · Shift 1

   What is the equilibrium expression for the reaction ${\mathrm{P}}_4(\mathrm{s})+5{\mathrm{O}}_2\leftrightharpoons {\mathrm{P}}_4{\mathrm{O}}_{10}(\mathrm{s})$?

   1. A.$K_c=[{\mathrm{P}}_4{\mathrm{O}}_{10}]/5[{\mathrm{P}}_4][{\mathrm{O}}_2]$
   2. B.$K_c=1/[{\mathrm{O}}_2{]}^5$
   3. C.$K_c=[{\mathrm{P}}_4{\mathrm{O}}_{10}]/[{\mathrm{P}}_4][{\mathrm{O}}_2{]}^5$
   4. D.$K_c=[{\mathrm{O}}_2{]}^5$
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   Answer: B

4. Q1672004 · 24 Apr 2004 · Shift 1

   The equilibrium constant for the reaction ${\mathrm{N}}_2(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})\leftrightharpoons 2NO(\mathrm{g})$ at temperature T is $4\times 10^{-4}$. The value of $K_c$ for the reaction $\mathrm{NO}(\mathrm{g})\leftrightharpoons \frac{1}{2}{\mathrm{N}}_2(\mathrm{g})+\frac{1}{2}{\mathrm{O}}_2(\mathrm{g})$ at the same temperature is :

   1. A.$2.5\times 10^2$
   2. B.$4\times 10^{-4}$
   3. C.50
   4. D.0.02
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   Answer: C

5. Q1682004 · 24 Apr 2004 · Shift 1

   The molar solubility (in $\mathrm{mol}{\mathrm{L}}^{-1}$) of a sparingly soluble salt $\mathrm{M}{\mathrm{X}}_4$ is "s". The corresponding solubility product is $K_{sp}$. 's' is given in terms of $K_{sp}$ by the relation :

   1. A.$s=(256K_{sp}{)}^{1/5}$
   2. B.$s=(128K_{sp}{)}^{1/4}$
   3. C.$s=(K_{sp}/128{)}^{1/4}$
   4. D.$s=(K_{sp}/256{)}^{1/5}$
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   Answer: D

6. Q1812004 · 24 Apr 2004 · Shift 1

   The standard e.m.f of a cell, involving one electron change is found to be 0.591 V at $25^{\circ }\mathrm{C}$. The equilibrium constant of the reaction is (F = 96,500 $\mathrm{C}\mathrm{mo}{\mathrm{l}}^{-1}$: R = 8.314 $\mathrm{J}{\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}$)

   1. A.$1.0\times 10^1$
   2. B.$1.0\times 10^{30}$
   3. C.$1.0\times 10^{10}$
   4. D.$1.0\times 10^5$
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   Answer: C

7. Q1822004 · 24 Apr 2004 · Shift 1

   The limiting molar conductivities ${\Lambda }^{\circ }$ for NaCl, KBr and KCl are 126, 152 and 150 $\mathrm{S}\mathrm{c}{\mathrm{m}}^2\mathrm{mo}{\mathrm{l}}^{-1}$ respectively. The ${\Lambda }^{\circ }$ for NaBr is

   1. A.128 $\mathrm{S}\mathrm{c}{\mathrm{m}}^2\mathrm{mo}{\mathrm{l}}^{-1}$
   2. B.278 $\mathrm{S}\mathrm{c}{\mathrm{m}}^2\mathrm{mo}{\mathrm{l}}^{-1}$
   3. C.176 $\mathrm{S}\mathrm{c}{\mathrm{m}}^2\mathrm{mo}{\mathrm{l}}^{-1}$
   4. D.302 $\mathrm{S}\mathrm{c}{\mathrm{m}}^2\mathrm{mo}{\mathrm{l}}^{-1}$
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   Answer: A