Mole Concept & Stoichiometry · JEE Main previous year questions

2012 4 questions

1. Q662012 · 26 May 2012 · Shift 1

   One mole of an ideal gas is expanded isothermally and reversibly to half of its initial pressure. $\Delta S$ for the process in $\mathrm{J}{\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}$ is $[\ln 2=0.693\text{ and }R=8.314J/(\mathrm{mol}\mathrm{K})]$

   1. A.6.76
   2. B.5.76
   3. C.10.76
   4. D.8.03
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   Answer: B

2. Q672012 · 26 May 2012 · Shift 1

   One mole of ${\mathrm{O}}_{2(\mathrm{g})}$ and two moles of $\mathrm{S}{\mathrm{O}}_{2(\mathrm{g})}$ were heated in a closed vessel of one-litre capacity at 1098 K. At equilibrium 1.6 moles of $\mathrm{S}{\mathrm{O}}_{3(\mathrm{g})}$ were found. The equilibrium constant $K_c$ of the reaction would be

   1. A.30
   2. B.40
   3. C.80
   4. D.60
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   Answer: C

3. Q752012 · 12 May 2012 · Shift 1

   The ppm level of ${\mathrm{F}}^{-}$ in a $500\mathrm{g}$ sample of a tooth paste containing $0.2\mathrm{g}{\mathrm{F}}^{-}$ is

   1. A.400
   2. B.1000
   3. C.250
   4. D.200
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   Answer: A

4. Q612012 · 7 May 2012 · Shift 1

   The concentrated sulphuric acid that is peddled commercially is 95% ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ by weight. If the density of this commercial acid is $1.834\mathrm{g}\mathrm{c}{\mathrm{m}}^{-3}$, the molarity of this solution is

   1. A.17.8 M
   2. B.12.0 M
   3. C.10.5 M
   4. D.15.7 M
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   Answer: A