Electrochemistry - 1
1.
Iron tablets can be bought at chemists to supplement the diet. They contain FeSO
4
. Which one of the following aqueous reagents could be used under suitable conditions to determined the percentage of iron in the tablets by titration?
a) Oxalic acid
b) Potassium per manganate
c) Sulphuric acid
d) Iodine in potassium iodide
2.
Some data relating to magnesium and its compounds are as follows:-
Standard electrode potential of magnesium = 238V
Melting point of Magnesium oxide = 28500C
Melting point of Magnesium chloride = 7140C
What is the most suitable method for extracting magnesium metal from its ores:-
a) Electrolysis of aqueous magnesium chloride
b) Electrolysis of Molten Magnesium oxide
c) Electrolysis of Molten Magnesium chloride
d) Reduction of Magnesium oxide with Carbon.
3.
Which one of the following is a property of a solution of dry hydrogen chloride in dry methylbenzene:-
a) It reacts with dry CuO on warming to give a blue solution.
b) It has a pH less than 7
c) It is a non-conductor of electricity
d) It reacts with magnesium to give hydrogen
4.
The emf of a simple cell was found to be 1.2 V under standard conditions. The following standard electrode potentials are given:-
a) E S+2 / S = -0.3V
b) Ep + / p = -1.8V
c) E R+ / R = -0.9V
d) EQ +2 / Q = + 0.3V
5.
Which one of the following explains why copper conducts electricity?
a) The bonding electrons in the crystal lattice move when a potential difference is applied.
b) The electric current causes the electrons to combine with Cu+2 ions.
c) The crystal lattice breaks down on applying a potential difference.
d) Cu+2 ions move to the cathode when a current is passed.
6.
Which one of the following elements has the same oxidation number in all of its known compounds?
a) Bromine
b) Chlorine
c) Nitrogen
d) Beryllium
7.
In which one of the following reactions does hydrogen behave as an oxidizing agent?
a) 2 Na + H
2
------ 2 NaH
b) N
2
+ 3H
2
-------- 2 N H
3
c) C
2
H
4
+ H
2
------- C
2
H
6
d) H
2
+ Cl
2
------- 2 Hcl
8.
What changes in oxidation number takes place when copper reacts with concentrated nitric acid to give a blue solution and a brown acidic gas?
a) 1 1
b) 2 1
c) 1 2
d) 2 2
9.
In an experiment, 50 Cm
3
of a 0.1 mol dm
-3
solution of a metallic salt reacted exactly with 25Cm
3
of 0.1 mol dm-3 aqueous sodium sulphite. The half equation for oxidation of sulphite con is shown below:
SO
3
-2 (aq) + H
2
O (l) SO
4
-2 (aq) + 2H+ (aq) + 2e-
If the original oxidation No. of the metal in the salt was 3, what would be the new oxidation number of the metal?
a) Zero
b) 2.0
c) 1.0
d) 4.0
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