It is desired to convert the energy derived from the combustion of propane into electrical energy, via a fuel cell. Given that the standard free energies of formation of $C_3{H}_8 \left(g\right), H_{2}O\left(l\right) and C{O}_2 \left(g\right)$ are -23.5, -237.2 and -394.4 $kJ mo{l}^{-1}$ respectively, calculate the standard EMF of the propane fuel cell.

(1) 1.10 V                                           

(2) 2.10V

(3) 3.12 V                                           

(4) 4.12 V

The temperature coefficient of a standard Cd-cell is $–5.0 \times {10}^{-5} V{k}^{-1}$ whose emf at $25°C$ is 1.018 V. During the cell operation, the temperature will -

(1) increase                                      

(2) decreases

(3) either                                         

(4) remains constant

Na-amalgam is prepared by electrolysis of NaCl solution using liquid Hg as a cathode. How

long should the current of 10 amp. is passed to produce 10% Na – Hg on a cathode of 10

gm Hg. (atomic mass of Na = 23).

(A) 7.77 min.                                               

(B) 9.44 min.

(C) 5.24 min.                                               

(D) 11.39 min.

The standard reduction potential of a silver chloride electrode is 0.2 V and that of a silver electrode is 0.79 V. The maximum amount of AgCl that can dissolve in ${10}^6 L of a 0.1 M AgN{O}_3$ solution is 

(1) 0.5 mmol                                              

(2) 1.0 mmol

(2) 2.0 mmol                                             

(4) 2.5 mmol

The $k=$ $4.95$ $\times$ ${10}^{-5}S$ $c{m}^{-1}$ for a 0.00099 M solution. The reciprocal of the degree of dissociation of acetic acid, if ${\wedge }_m^0$ for acetic acid is 400 S $c{m}^{2}mo{l}^{-1}$ will be:

Pure water is saturated with pure solid AgCl, a silver electrode is placed in the solution and the potential is measured against normal calomel electrode at $25°C$. This experiment is then repeated with a saturated solution of AgI. If the difference in potential in the two cases is 0.177 V. What is the ratio of solubilities of AgCl and AgI at the temperature of the experiment ?

$\left(1\right) {10}^3$

$\left(2\right) {10}^6$

$\left(3\right) {10}^4$

$\left(4\right) {10}^2$

A hydrogen electrode X was placed in a buffer solution of sodium acetate and acetic acid in the ratio a : b and another hydrogen electrode Y was placed in a buffer solution of sodium acetate and acetic acid in the ratio b : a. If reduction potential values for two cells are found to be $E_{1}and E_2$ respectively with respect to standard hydrogen electrode, the $p{K}_a$ value of the acid can be given as

(1) $\frac{E_1-E_2}{0.118}$                                           

(2) $\frac{E_1+E_2}{0.118}$

(3) $\frac{E_1}{E_2}\times 0.118$                                      

(4) $\frac{E_2-E_1}{0.118}$

Calculate the useful work of the reaction \(Ag(s) + {1 \over 2} Cl_2(g) \rightarrow AgCl(s)\) 

$Given,$
${E^{°}}_{C{l}_2/C{l}^{-}}=+1.36 V, {E^{°}}_{AgCl/Ag,C{l}^{-}}=0.22 V$
$If P_{C{l}_2}=1 atm and T=298 K$

(1) 110 kJ/mol

(2) 220 kJ/mol

(3) 55 kJ/mol

(4) 1000 kJ/mol

A resistance of 50$\Omega$ is registered when two electrodes are suspended into a beaker containing a dilute solution of a strong electrolyte such that exactly half of the them are submerged into solution. If the solution is diluted by adding pure water (negligible conductivity) so as to just completely submerge the electrodes, the new resistance offered by the solution would be

(1) \(50 \Omega\)                                       

(2) \(100   \Omega\)

(3) \(25 \Omega\)                                       

(4) \(200 \Omega\)

The magnitude of the emf of the following cell \(at ~25^{\circ} \mathrm{C} \) is:
\(P t\left(H_2\right) \mid 0.1 M\text{ acetic acid+ 0.1 M sodium acetate} ~\\\| ~0.1 \mathrm{M}\text{ formic acid + 0.1 M}\text{ sodium formate} \mid P t\left(H_2\right) \)

\( \left(\text { Use } K_{a(\text { acetic acid })}=1.8 \times 10^{-5} \text { and } K_{a(\text { Formic acid })} \\=2.1 \times 10^{-4}\right)\) 
1. 0.0315 volt
2. 0.0629 volt
3. 0.0455 volt
4. 0.0545 volt