Chemical Thermodynamics · JEE Main previous year questions

2020 8 questions

1. Q572020 · 6 Sept 2020 · Shift 2

   For the given cell : $$\mathrm{Cu}(\mathrm{s})\mid \mathrm{C}{\mathrm{u}}^{2+}({\mathrm{C}}_1\mathrm{M})\parallel \mathrm{C}{\mathrm{u}}^{2+}({\mathrm{C}}_2\mathrm{M})\mid \mathrm{Cu}(\mathrm{s})$$ change in Gibbs energy ($\Delta G$) is negative, if :

   1. A.$C_2=\sqrt{2}{C}_1$
   2. B.$C_2=\frac{C_1}{\sqrt{2}}$
   3. C.$C_1=2C_2$
   4. D.$C_1=C_2$
   Show answer

   Answer: A

2. Q712020 · 2 Sept 2020 · Shift 1· Numerical answer

   The Gibbs change (in J) for the given reaction at $[\mathrm{C}{\mathrm{u}}^{2+}]=[\mathrm{S}{\mathrm{n}}^{2+}]=1\mathrm{M}$ and $298\mathrm{K}$ is : $\mathrm{Cu}(\mathrm{s})+\mathrm{S}{\mathrm{n}}^{2+}(aq.)\to \mathrm{C}{\mathrm{u}}^{2+}(aq.)+\mathrm{Sn}(\mathrm{s})$; $(E_{\mathrm{S}{\mathrm{n}}^{2+}|Sn}^0=-0.16\mathrm{V},$ $E_{\mathrm{C}{\mathrm{u}}^{2+}|Cu}^0=0.34\mathrm{V})$ Take $\mathrm{F}=96500\mathrm{C}\mathrm{mo}{\mathrm{l}}^{-1})$

   Show answer

   Answer: 96500

3. Q732020 · 2 Sept 2020 · Shift 2· Numerical answer

   The heat of combustion of ethanol into carbon dioxide and water is $-327\mathrm{kcal}$ at constant pressure. The heat evolved (in cal) at constant volume and $27^{\circ }\mathrm{C}$ (if all gases behave ideally) is ($\mathrm{R}=2\mathrm{cal}\mathrm{mo}{\mathrm{l}}^{-1}{\mathrm{K}}^{-1}$) _______.

   Show answer

   Answer: 326400

4. Q532020 · 9 Jan 2020 · Shift 1
   
   1. A.(b) < (c) < (a)
   2. B.(a) < (c) < (b)
   3. C.(a) < (b) < (c)
   4. D.(c) < (b) < (a)
   Show answer

   Answer: C

5. Q532020 · 8 Jan 2020 · Shift 1

   The third ionization enthalpy is minimum for :

   1. A.Ni
   2. B.Co
   3. C.Mn
   4. D.Fe
   Show answer

   Answer: D

6. Q732020 · 8 Jan 2020 · Shift 1· Numerical answer
   
   Show answer

   Answer: 68

7. Q582020 · 8 Jan 2020 · Shift 2

   For the following Assertion and Reason, the correct option is : Assertion : The pH of water increases with increase in temperature. Reason : The dissociation of water into ${\mathrm{H}}^{+}$ and ${\mathrm{OH}}^{-}$ is an exothermic reaction.

   1. A.Both assertion and reason are false.
   2. B.Both assertion and reason are true, but the reason is not the correct explanation for the assertion.
   3. C.Both assertion and reason are true, and the reason is the correct explanation for the assertion.
   4. D.Assertion is not true, but reason is true.
   Show answer

   Answer: A

8. Q712020 · 7 Jan 2020 · Shift 2· Numerical answer

   The standard heat of formation $({\Delta }_f{H}_{298}^{\circ })$ of ethane (in kJ/mol), if the heat of combustion of ethane, hydrogen and graphite are - 1560, -393.5 and -286 kJ/mol, respectively is :

   Show answer

   Answer: -192.5