A device that converts energy of the combustion of fuels like hydrogen and methane, directly

into electrical energy is known as:

1. Fuel cell

2. Electrolytic cell

3. Dynamo

4. Ni-Cd cell

 $F_2$ gas can’t be obtained by the electrolysis of any $F^{-1}$salt because-

1. Fluorine is the strongest reducing agent

2. Fluorine is the strongest oxidising agent.

3. Fluorine easily combine with atmospheric $O_2$

4. All

If the E°_cell for a given reaction has a negative value then which of the following gives the

correct relationships for the values of $∆$G° and K_eq?

1. $∆$G° < 0;K_eq > 1

2. $∆$G° < 0; K_eq < 1

3. $∆$G°> 0; K_eq < 1

4. $∆$G° > 0; K_eq > 1

Acetic acid has K_a = 1.8 × 10^–5 while formic acid had K_a = 2.1 × 10^–4. What would be the magnitude of the emf of the cell

Pt(H₂) $\left|\begin{array}{l}0.1\mathrm{M}<mspace\; width="1em"></mspace>\mathrm{acetic}<mspace\; width="1em"></mspace>\mathrm{acid}+\\ 0.1\mathrm{M}<mspace\; width="1em"></mspace>\mathrm{sodium}<mspace\; width="1em"></mspace>\mathrm{acetate}\end{array}\right|\left|\begin{array}{l}0.1\mathrm{M}<mspace\; width="1em"></mspace>\mathrm{formic}<mspace\; width="1em"></mspace>\mathrm{acid}+\\ 0.1\mathrm{M}<mspace\; width="1em"></mspace>\mathrm{sodium}<mspace\; width="1em"></mspace>\mathrm{formate}\end{array}\right|$ Pt(H₂) at 25°C

(1) 0.0315 volt

(2) 0.0629 volt

(3) 0.0455 volt

(4) 0.0545 volt

The same amount of electric current is apassed through aqueous solution of MgSO₄ and AlCl₃. If 2.8 g Mg metal is deposited at amount of Al metal deposited in second cell will be

1. 2.1 g

2. 2.49 g

3. 3.15 g

4. 3.73g

${\mathrm{E}}_{\raisebox{1ex}{${\mathrm{Ni}}^{+2}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{Ni}$}\right.}^0<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>-0.25<mspace\; width="1em"></mspace>\mathrm{V},<mspace\; width="1em"></mspace>{\mathrm{E}}_{\raisebox{1ex}{${\mathrm{Au}}^{+3}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{Au}$}\right.}^0<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>1.50<mspace\; width="1em"></mspace>\mathrm{V}$

the emf of Voltaic cell

$\mathrm{Ni}<mspace\; width="1em"></mspace>|<mspace\; width="1em"></mspace>{\mathrm{Ni}}^{+2}(1\mathrm{M})<mspace\; width="1em"></mspace>||<mspace\; width="1em"></mspace>{\mathrm{Au}}^{+3}(1\mathrm{M})<mspace\; width="1em"></mspace>\mathrm{Au}<mspace\; width="1em"></mspace>\mathrm{is}:-$

(1) 1.25 V

(2) -1.75 V

(3) 1.75 V

(4) 4 V

For the cell reaction

${\mathrm{Cu}}_{{\mathrm{c}}_1}^{+2}<mspace\; width="1em"></mspace>\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace>+\hspace{0.17em}\mathrm{Zn}\left(\mathrm{s}\right)<mspace\; width="1em"></mspace>\stackrel{<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>}{\to }<mspace\; width="1em"></mspace>{\mathrm{Zn}}_{{\mathrm{C}}_2}^{+2}<mspace\; width="1em"></mspace>\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>\mathrm{Cu}\left(\mathrm{s}\right)$

the change in free energy at a given temperature is a function of 

(1) lnC₁

(2) ln$\frac{{\mathrm{C}}_2}{{\mathrm{C}}_1}$ 

(3) ln (C₁ +C₂)

(4) lnC₂

The cell reaction of micro electrochemical cell formed during rusting of iron is:-

1.  ${\mathrm{O}}_2\left(\mathrm{g}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>4{\mathrm{H}}^{\oplus }\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>4{\mathrm{e}}^{-}<mspace\; width="1em"></mspace>\to <mspace\; width="1em"></mspace>2{\mathrm{H}}_2\mathrm{O}<mspace\; width="1em"></mspace>\left(\mathrm{l}\right)$

2. $4{\mathrm{Fe}}^{+2}\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{O}}_2\left(\mathrm{g}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)<mspace\; width="1em"></mspace>\to <mspace\; width="1em"></mspace>4\mathrm{FeO}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>4{\mathrm{H}}^{\oplus }\left(\mathrm{aq}\right)$

3. $2\mathrm{Fe}\left(\mathrm{s}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{O}}_2\left(\mathrm{g}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>4\mathrm{H}{°}^{\oplus }\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace>\to 2{\mathrm{Fe}}^{+2}\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)$

4.  $\mathrm{Fe}\left(\mathrm{s}\right)<mspace\; width="1em"></mspace>\to {\mathrm{Fe}}^{+2}\left(\mathrm{aq}\right)<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2{\mathrm{e}}^{-}$

What will be the value of $∆\mathrm{G}°$ for the rection ${\mathrm{Cu}}^{+2}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>\mathrm{Fe}<mspace\; width="1em"></mspace>\stackrel{<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>}{\rightleftharpoons }<mspace\; width="1em"></mspace>{\mathrm{Fe}}^{+2}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>\mathrm{Cu}<mspace\; width="1em"></mspace>,<mspace\; width="1em"></mspace>$

if ${\mathrm{E}}_{\raisebox{1ex}{${\mathrm{Cu}}^{+2}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{Cu}$}\right.}^{\circ }<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>+0.34<mspace\; width="1em"></mspace>\mathrm{V}<mspace\; width="1em"></mspace>\mathrm{and}<mspace\; width="1em"></mspace>{\mathrm{E}}_{\raisebox{1ex}{${\mathrm{Fe}}^{+2}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{Fe}$}\right.}^{\circ }<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>-0.44<mspace\; width="1em"></mspace>\mathrm{V}$$$

(1) -65.62 KJ

(2) -75.27 KJ

(3) -150.54 KJ

(4) +150.54 KJ

$2{\stackrel{\oplus }{\mathrm{Ag}}}_{\left(\mathrm{aq}\right)}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{Cu}}_{\left(\mathrm{s}\right)}<mspace\; width="1em"></mspace>\stackrel{<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>}{\rightleftharpoons }<mspace\; width="1em"></mspace>{{\mathrm{Cu}}_{\left(\mathrm{aq}\right)}}^{+2}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2{\mathrm{Ag}}_{\left(\mathrm{s}\right)}$

The cell potential for this reaction is 0.46V. Which of the following change will increase the potential the most ?

(1) $\left[\stackrel{\oplus }{\mathrm{Ag}}\right]$ concentration is doubled

(2) [Cu²⁺] concentration is halved

(3) Size of Cu_(s) electrode is doubled

(4) size of Ag_(s) electrode is decreased to half