Chemical Thermodynamics · JEE Main previous year questions

2017 3 questions

1. Q662017 · 9 Apr 2017 · Shift 1

   A gas undergoes change from state A to state B. In this process, the heat absorbed and work done by the gas is 5 J and 8 J, respectively. Now gas is brought back to A by another process during which 3 J of heat is evolved. In this reverse process of B to A :

   1. A.10 J of the work will be done by the gas.
   2. B.6 J of the work will be done by the gas.
   3. C.10 J of the work will be done by the surrounding on gas.
   4. D.6 J of the work will be done by the surrounding on gas.
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   Answer: D

2. Q682017 · 8 Apr 2017 · Shift 1

   The enthalpy change on freezing of 1 mol of water at $5^{\circ }\mathrm{C}$ to ice at $-5^{\circ }\mathrm{C}$ is : (Given ${\Delta }_{\mathrm{fus}}\mathrm{H}=6\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$ at $0^{\circ }\mathrm{C}$, ${\mathrm{C}}_{\mathrm{p}}({\mathrm{H}}_2\mathrm{O},\ell )=75.3\mathrm{J}\mathrm{mo}{\mathrm{l}}^{-1}{\mathrm{K}}^{-1}$ ${\mathrm{C}}_{\mathrm{p}}({\mathrm{H}}_2\mathrm{O},\mathrm{s})=36.8\mathrm{J}\mathrm{mo}{\mathrm{l}}^{-1}{\mathrm{K}}^{-1}$)

   1. A.$5.44\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
   2. B.$5.81\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
   3. C.$6.56\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
   4. D.$6.00\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$
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   Answer: C

3. Q722017 · 8 Apr 2017 · Shift 1

   Consider the following ionization enthalpies of two elements 'A' and 'B' . | Element | Ionization enthalpy (kJ/mol) | | | |---|---|---|---| | | $1^{\mathrm{st}}$ | $2^{\mathrm{nd}}$ | $3^{\mathrm{rd}}$ | | A | 899 | 1757 | 14847 | | B | 737 | 1450 | 7731 | Which of the following statements is correct ?

   1. A.Both ‘A’ and ‘B’ belong to group-1where ‘B’ comes below ‘A’.
   2. B.Both ‘A’ and ‘B’ belong to group-1 where ‘A’ comes below ‘B’.
   3. C.Both ‘A’ and ‘B’ belong to group-2 where ‘B’ comes below ‘A’.
   4. D.Both ‘A’ and ‘B’ belong to group-2 where ‘A’ comes below ‘B’.
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   Answer: C