Electrolysis I Revision MCQ Questions

1.    During the electrolysis of concentrated sodium chloride using platinum electrodes, which of the following would be the correct observations at each electrode?Electrolysis 1 MCQ1.PNG


2. Which of the following equations represents the reaction that takes place at the cathode during the electrolysis of aqueous silver nitrate with carbon electrodes?

A    Ag+ (aq) + e –> Ag (s)

B    2H+ (aq) + 2e –> H2(Q)

C    2N3- (aq) –>  N2(aq) + 6e

D    4OH (aq) –> O2 (g) + 2H2O (I) + 4e


3. Electrolysis of the following electrolytes (using inert electrodes) give the same product at the cathode except

A    dilute sulfuric acid

B    aqueous sodium chloride

C    aqueous copper (II) sulphate

D    concentrated potassium hydroxide


4. Element X is extracted by the electrolysis of a molten compound of elements X and Y. The electrode reactions are as shown.
At the cathode: X2+ (I) + 2e –> x (I)
At the anode: 2Y2- (I) –> Y2 (g) + 4e

A    Aluminium oxide

B    Calcium chloride

C    Magnesium oxide

D    Potassium chloride


5. During the electrolysis of molten silver bromide using graphite electrodes, what will be the mass of the products collected at each electrode when 0.5 mol of electrons was passed through the electrolytic cell?

Electrolysis 1 MCQ5.PNG


6. A solid deposit of element R is formed at the cathode when an aqueous solution containing ions of R is electrolysed. Which statement about element R is correct?

A    Element R is below hydrogen in the reactivity series.

B    R gains electrons to form ions at the cathode.

C    Element R forms negatively charged ions.

D    Ions of R loses electrons at the cathode.




Answer:

1.    B

2.    A

3.    C

4.    C

5.    B

6.    A

Advertisements

Atomic Bonding Revision Structured Questions

1.     P, Q, R, X, Y and Z are consecutive elements of the Periodic Table. The table below shows the formulae of the oxide compounds of these elements. Atomic bonding SQ1.PNG

(a)    In which Group of the Periodic Table would you expect to find

(i)    element P : ______________________________________

(ii)    element Y : ______________________________________

(iii)    element Z : _____________________________________

(b)    What is the formula of the compound formed between the elements
P and X?

(c)    Which of the oxide in the table above is an ionic compound? Give a reason for your answer.

(d) Write a balanced chemical equation to show the reaction of element Z in air to form Z2O.


2.    Silicon and carbon are both in Group IV of the Periodic Table.

(a)    Draw a diagram of an atom of silicon showing how the electrons are arranged and the numbers of protons and neutrons in the nucleus.

(b)    Both carbon and silicon form oxides in which the bonding between the atoms is covalent. Carbon dioxide has a simple molecular structure whereas silicon(IV) oxide (silicon dioxide) has a macromolecular structure.

(i)    Draw a dot-and-cross diagram (showing only valence electrons) to show the bonding in a molecule of carbon dioxide.

(ii)    The structure of silicon(IV) oxide is as drawn below Atomic bonding SQ2bii.PNG

Silicon(IV) oxide is a solid whereas carbon dioxide is a gas.
Explain this difference in terms of the structures of the two oxides.

(iii)    Does silicon(IV) oxide, conduct electricity?
Explain your answer with reference to its structure.


3.    (a) The table below shows the number of electrons and neutrons for ions A2-, B+, C3- and D2+Atomic bonding SQ3a.PNG

(i)      State the nucleon number of the 4 ions.
(ii)     Give the electronic configuration of D.
(iii)    What is the formula of the compound formed between A and B?

(b)    Some physical properties of iron, sulfur and iron (II) sulfide are shown in the table below.Atomic bonding SQ3b.PNG

(i)    Do you expect iron (II) sulfide to conduct electricity in the liquid state? Give a reason for your answer.

(ii)    Account for the difference in the electrical conductivity between iron and iron (II) sulfide in the solid state.

(iii)    Explain, in terms of the structure and bonding, the difference in the melting points between sulfur and iron (II) sulfide.




Answer:

1(a)(i) IV
(ii) 0
(iii) I
(b) PX4 1
(c) Z2O (Z is also accepted)
Z is in group I of the periodic table and hence, a metal.
Metal combines with oxygen which is a non-metal to form ionic compound.
(d) 4 Z + O2 –> 2 Z2O


2 (a)

atomic bonding SQ2a.PNG

(b)

ato,ic bonding SQ2b.PNG


3 (a)(i)

ato,ic bonding SQ3a.PNG

(ii) 2.8.8.2

(iii) B2A

(b)(i) Yes, the ions are free to move in the liquid state.

(ii) In solid state, the iron(II) ions and sea of electrons are joined by metallic bonds. The delocalised electrons can conduct electricity.
Iron(ll) sulphide cannot conduct electricity in the solid state because the ions are not free to move in the ionic lattice.

(iii) Sulfur has low melting point because of the weak intermolecular forces between the molecules. thus lesser amount of energy is need to overcome these forces. [1]
lron(ll) sulfide has high melting point because it is an ionic compound with strong electrostatic forces between oppositely charged iron and sulfide ions thus larger amount of energy is needed to overcome these forces.

Atomic Bonding Revision MCQ Questions

1.    A colourless crystalline solid melts below 150oC and dissolves in water to give a solution that does not conduct electricity. The solid may be

A    sodium chloride, NaCl

B    silicon dioxide, SiO2

C    copper, Cu

D    glucose, C6H12O6


2.    X, Y and Z are three elements with consecutive proton numbers. X has
the lowest proton number and Y is a noble gas. How is a stable compound formed between X and Z ?

A    Each atom of X shares a pair of electrons with an atom of Z.

B    Each atom of X receives an electron from an atom of Z to form X+Z.

C    Each atom of X gives an electron to an atom of Z to form XZ+ .

D    Each atom of X receives an electron from an atom of Z to form XZ+ .


3.    In which of the following is there no covalent bond?

A    diamond

B    aluminium fluoride

C    sodium sulfate

D    sulfur dioxide


4.    The elements X and Y form the compound X2Y. What is the correct electronic arrangement of the atoms of X and Y? Atomic bonding Q4.PNG


5.    Which substance in the table could be hydrogen chloride? Atomic bonding Q5.PNG


6.    When solid iodine is heated, it changes into a purple gas without passing through the liquid state. In this process

A    covalent bonds between iodine atoms are broken.

B    covalent bonds between iodine molecules are broken.

C    ionic forces between iodine atoms are overcome.

D    attractive forces between iodine molecules are overcome.


7.     The elements T, X and Y have consecutive, increasing atomic numbers. If element T is noble gas, what will be the symbol for the ion of element Y in its compounds?

A    Y3+

B    Y2-

C    Y+

D    Y2+


8.    A stable molecule containing atoms of the elements X, Y and Z has the following structure. Atomic bonding Q8.PNG


9.    Which structural feature of graphite best accounts for its use as a lubricant?

A    delocalized electrons

B    hexagonal arrangement of carbon atoms

C    strong covalent bonds within layers

D    weak Van der Waals’ forces between layers


10.    A substance contains the ions X4+ and Y2-. What is the simplest formula of the compound containing the ion X4+ and Y2-?

A X2Y4

B X4Y2

C XY2

D X2Y


11.    The equation below shows the reaction between element X and dilute
hydrochloric acid.
X (s) + 2HCl (aq) → XCl2(aq) + H2 (g)

Which types of bonding are present in element X and compound XCl2? Atomic bonding Q11.PNG


12.    Elements X and Y are both non-metallic elements in the Periodic Table. Element X combines with carbon to give the structural formula of X=C=X. Element Y combines with hydrogen to give the structural formula of H-Y.

What is the most likely structural formula of the covalent compound X2Y2?

A    X-Y-Y-X

B    X=Y-Y=X

C    Y-X-X-Y

D    Y-X-Y-X




Answer:

1.    D

2.    D

3.    B

4.    D

5.    A

6.    D

7.    D

8.    C

9.    D

Atoms and Molecules Revision Structured Question

The following questions refer to the diagram below.A2M SQ.PNG

Answer the following questions using the gases listed below.

hydrogen (H2)     oxygen (O2)     helium (He)
nitrogen (N2)     methane (CH4)     carbon monoxide (CO)

Each gas may be chosen once, more than once, or not at all

(a)    Which two gases, when placed into A and B respectively, will cause the water level at P to move up initially? Explain your answer.

 

 

 

(b)    What would be observed in the diagram above if A is helium at room
temperature and B is helium at 60°C? Explain your answer.

 

 

 




Answer:

(a) A: oxygen
B:hydrogen/methane/ helium
Oxygen has higher relative molecular mass than air, faster outward diffusion of air.
Hydrogen/methane/helium has a lower relative molecular mass than air, faster               inward diffusion of gas.

(b) Water level at P rises while water level at Q drops.
Helium at higher temperature has higher kinetic energy and diffuses faster into             the porous pot.

Atoms and Molecules Revision MCQ Questions

1.    A beaker of nitrogen was inverted over a porous pot containing carbon monoxide as shown. The water level did not change. What is the reason for this? A2M Q1.PNG

A    Both gases are diatomic.

B    Nitrogen is an unreactive gas.

C    The gas particles are too large to pass through porous pot.

D    The two gases have the same density.


2.    Hydrogen chloride is very soluble in water, whereas chlorine is only slightly soluble in water. Both gases can be dried using concentrated sulfuric acid. Which diagram represents the correct method of obtaining dry chlorine from damp chlorine containing a small amount of hydrogen chloride?

A2M Q2.PNG




Answer:

1.    D

2.    B