1
IIT-JEE 2010 Paper 1 Offline
MCQ (Single Correct Answer)
+4
-1
The concentration of potassium ions inside a biological cell is at least twenty times higher than the outside. The resulting potential difference across the cell is important in several processes such as transmission of nerve impulses and maintaining the ion balance. A simple model for such a concentration cell involving a metal M is :
M(s) | M+ (aq ; 0.05 molar) || M+ (aq ; 1 molar) | M(s)
For the above electrolytic cell the magnitude of the cell potential | Ecell | = 70 mV.

If the 0.05 molar solution of M+ is replaced by a 0.0025 molar M+ solution, then the magnitude of the cell potential would be :
A
35 mV
B
70 mV
C
140 mV
D
700 mV
2
IIT-JEE 2010 Paper 1 Offline
MCQ (Single Correct Answer)
+4
-1
The concentration of potassium ions inside a biological cell is at least twenty times higher than the outside. The resulting potential difference across the cell is important in several processes such as transmission of nerve impulses and maintaining the ion balance. A simple model for such a concentration cell involving a metal M is :
M(s) | M+ (aq ; 0.05 molar) || M+ (aq ; 1 molar) | M(s)
For the above electrolytic cell the magnitude of the cell potential | Ecell | = 70 mV.

For the above cell :
A
Ecell < 0 ; $$\Delta G > 0$$
B
Ecell > 0 ; $$\Delta G < 0$$
C
Ecell < 0 ; $$\Delta G^o > 0$$
D
Ecell > 0 ; $$\Delta G^o > 0$$
3
IIT-JEE 2008 Paper 2 Offline
MCQ (Single Correct Answer)
+3
-1

Electrolysis of dilute aqueous NaCl solution was carried out by passing 10 milli ampere current. The time required to liberate 0.01 mol of H$$_2$$ gas at the cathode is (1 Faraday = 96500 C mol$$^{-1}$$].

A
9.65 $$\times$$ 10$$^4$$ sec
B
19.3 $$\times$$ 10$$^4$$ sec
C
28.95 $$\times$$ 10$$^4$$ sec
D
38.6 $$\times$$ 10$$^4$$ sec
4
IIT-JEE 2007 Paper 2 Offline
MCQ (Single Correct Answer)
+3
-1

Redox reactions play a pivotal role in chemistry and biology. The values of standard redox potential $$\left(\mathrm{E}^{\circ}\right)$$ of two half-cell reactions decide which way the reaction is expected to proceed. A simple example is a Daniel cell in which zinc goes into solution and copper gets deposited. Given below are a set of half-cell reactions (acidic medium) along with their $$\mathrm{E}^{\circ}$$ (V with respect to normal hydrogen electrode) values. Using this data obtain the correct explanations.

$$\begin{array}{ll} \mathrm{I}_{2}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{I}^{-} & \mathrm{E}^{\mathrm{o}}=0.54 \\ \mathrm{Cl}_{2}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cl}^{-} & \mathrm{E}^{\mathrm{o}}=1.36 \\ \mathrm{Mn}^{3+}+\mathrm{e}^{-} \rightarrow \mathrm{Mn}^{2+} & \mathrm{E}^{\mathrm{o}}=1.50 \\ \mathrm{Fe}^{3+}+\mathrm{e}^{-} \rightarrow \mathrm{Fe}^{2+} & \mathrm{E}^{\mathrm{o}}=0.77 \\ \mathrm{O}_{2}+4 \mathrm{H}^{+}+4 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_{2} \mathrm{O} & \mathrm{E}^{\mathrm{o}}=1.23 \end{array}$$

Among the following, identify the correct statement.

A
Chloride ion is oxidised by $$\mathrm{O}_{2}$$
B
$$\mathrm{Fe}^{2+}$$ is oxidised by iodine
C
Iodide ion is oxidised by chlorine
D
$$\mathrm{Mn}^{2+}$$ is oxidised by chlorine

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