Chemistry 2
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UNIVERSITY ENTRANCE EXAMINATION
CHEMISTRY
Duration
: 2 hours
Please read the follow instructions carefully. 1.
This examination has TWO (2) sections – A and B, and comprises SIX (6) printed pages.
2.
Attempt all sections.
3.
Answer all questions in section A. Indicate your answers on the answer paper provided. Each question carries 2 marks. Marks will not be deducted for wrong answers.
4.
Answer any THREE (3) questions in section B. Write your answers on the answer paper provided. Begin each question with a fresh sheet of paper. Write the question number clearly. Each question carries 20 marks.
5.
At the end of the examination, attach the cover paper on top of your answer script. Complete the information required on the cover page and tie the papers together with the string provided.
6.
Do not take any paper, including the question paper and unused answer paper, out of the examination hall.
SECTION A
(40 Marks)
Answer All Questions. (2 marks for each question).
1.
How many lone pairs are there at C in CO32-? A B C D E
2.
How many lone pairs are there at N in NH4+? A B C D E
3.
redox addition disproportionation condensation none of the above
CH2N2 readily liberates CH2. This statement is most likely _____ A B C D E
5.
0 0.5 1 1.5 2
Reaction between NH3 with BH3 is an example of ______ reactions. A B C D E
4.
0 0.5 1 1.5 2
correct wrong only correct if H is replaced by R only correct if N is replaced by S unable to judge as the molecule is too unstable
The reaction CO2 + H2O Æ H2CO3 is most likely to produce quantitative yield of the product. This statement is most likely _____ A B C D E
correct wrong correct if CO2 is in excess correct if the solution is very diluted unable to judge since the pH is not known
2
6.
The N-N bond in N2H4 is likely to be ______ A B C D E
7.
Which of the following is a good example of a compound with A B C D E
8.
esterification photosynthesis Aldol condensation trans-esterification enzymatic photo-oxidation
In pyrophosphoric acid H4P2O7, there is/are _____ P-H bonds. A B C D E
10.
H3BO3 B2H6 NF3 all of the above none of the above
An important biosynthesis of carbohydrates in plants is _____ A B C D E
9.
weak and reactive weak and unreactive strong and reactive strong and unreactive unable to judge
0 1 2 3 4
Which of the following is (comparatively) most alkaline? A B C D E
sea water tomatoes black coffee (unpolluted) rain urine
3
π bond?
11.
The conjugate base of C2H5OH is ______ A B C D E
12.
10-9 is commonly expressed as ___ A B C D E
13.
fully filled half-filled empty half-filled but only in the excited state fully filled but only in the excited state
In H+, the s orbital is _____ A B C D E
15.
micro nano pico molecular meso
In H-, the s orbital is _____ A B C D E
14.
OHC2H5OC2H5+ CH3OO2-
fully filled half-filled empty half-filled but only in the excited state fully filled but only in the excited state
In the solid state structure of BeCl2, the major force among individual [BeCl2] molecules is likely to be _______ interactions. A B C D E
dipole-dipole interaction van der Waal interaction ionic covalent two of the above
4
16.
Scattering of light by a colloidal system is commonly called _______ effect. A B C D E
17.
The reaction between carboxylic acid and amine can be considered a/an ________ reaction. A B C D E
18.
oxidation reduction disproportionation hydrolysis none of the above
When table sugar dissolves in water, it mostly undergoes _______ A B C D E
20.
condensation addition redox hydrolysis metathesis
The reaction between NH4Cl and AgNCO gives urea, NH2COCH2. In the process, Ag+ undergoes ________ A B C D E
19.
Dalton Perkin Raman Tyndall Esosteric
hydrolysis solvolysis dissociation all of the above none of the above
How many pi (π) bonds are there in H2CO? A B C D E
0 1.0 1.5 2.0 none of the above 5
SECTION B
(60 Marks)
Answer three (3) of the following five (5) questions (20 marks for each question). (If there is any physical constant or data that you need in your calculation but which is not found in the question, you may denote them as “x”, “y”… etc, explain them, and indicate such clearly in your working process and answers)
1.
“Since H+ is highly acidic and since H2O undergoes protonation easily to give H3O+, it is likely that the latter would further react with H+ to give H4O2+ readily”. Examine this statement carefully by determining whether it is true or false and, if false, under what situation would the statement be valid. Explain.
2.
A mixture of acetaldehyde CH3CHO and propanal C2H5CHO under basic conditions would readily yield four products. Identify them and sketch carefully their structures.
3.
You are given the following ions, namely (a) CH3+; (b) CH2R+; (c) CHR2+; (d) CR3+. Arrange them in a descending arrangement carefully.
4.
5.
order
of
stability
and
explain
your
Sketch the Lewis structures of the following: (a)
H2SO5
(b)
HNO3
(c)
HClO3
What is the concentration of H3O+ in a 1.00 x 10-2 M NaOH solution? State clearly the assumptions, if any, you make. (Kw = 1.00 x 10-14)
END OF PAPER
6
CHEMISTRY
Duration
: 2 hours
Please read the follow instructions carefully. 1.
This examination has TWO (2) sections – A and B, and comprises SIX (6) printed pages.
2.
Attempt all sections.
3.
Answer all questions in section A. Indicate your answers on the answer paper provided. Each question carries 2 marks. Marks will not be deducted for wrong answers.
4.
Answer any THREE (3) questions in section B. Write your answers on the answer paper provided. Begin each question with a fresh sheet of paper. Write the question number clearly. Each question carries 20 marks.
5.
At the end of the examination, attach the cover paper on top of your answer script. Complete the information required on the cover page and tie the papers together with the string provided.
6.
Do not take any paper, including the question paper and unused answer paper, out of the examination hall.
SECTION A
(40 Marks)
Answer All Questions. (2 marks for each question).
1.
How many lone pairs are there at C in CO32-? A B C D E
2.
How many lone pairs are there at N in NH4+? A B C D E
3.
redox addition disproportionation condensation none of the above
CH2N2 readily liberates CH2. This statement is most likely _____ A B C D E
5.
0 0.5 1 1.5 2
Reaction between NH3 with BH3 is an example of ______ reactions. A B C D E
4.
0 0.5 1 1.5 2
correct wrong only correct if H is replaced by R only correct if N is replaced by S unable to judge as the molecule is too unstable
The reaction CO2 + H2O Æ H2CO3 is most likely to produce quantitative yield of the product. This statement is most likely _____ A B C D E
correct wrong correct if CO2 is in excess correct if the solution is very diluted unable to judge since the pH is not known
2
6.
The N-N bond in N2H4 is likely to be ______ A B C D E
7.
Which of the following is a good example of a compound with A B C D E
8.
esterification photosynthesis Aldol condensation trans-esterification enzymatic photo-oxidation
In pyrophosphoric acid H4P2O7, there is/are _____ P-H bonds. A B C D E
10.
H3BO3 B2H6 NF3 all of the above none of the above
An important biosynthesis of carbohydrates in plants is _____ A B C D E
9.
weak and reactive weak and unreactive strong and reactive strong and unreactive unable to judge
0 1 2 3 4
Which of the following is (comparatively) most alkaline? A B C D E
sea water tomatoes black coffee (unpolluted) rain urine
3
π bond?
11.
The conjugate base of C2H5OH is ______ A B C D E
12.
10-9 is commonly expressed as ___ A B C D E
13.
fully filled half-filled empty half-filled but only in the excited state fully filled but only in the excited state
In H+, the s orbital is _____ A B C D E
15.
micro nano pico molecular meso
In H-, the s orbital is _____ A B C D E
14.
OHC2H5OC2H5+ CH3OO2-
fully filled half-filled empty half-filled but only in the excited state fully filled but only in the excited state
In the solid state structure of BeCl2, the major force among individual [BeCl2] molecules is likely to be _______ interactions. A B C D E
dipole-dipole interaction van der Waal interaction ionic covalent two of the above
4
16.
Scattering of light by a colloidal system is commonly called _______ effect. A B C D E
17.
The reaction between carboxylic acid and amine can be considered a/an ________ reaction. A B C D E
18.
oxidation reduction disproportionation hydrolysis none of the above
When table sugar dissolves in water, it mostly undergoes _______ A B C D E
20.
condensation addition redox hydrolysis metathesis
The reaction between NH4Cl and AgNCO gives urea, NH2COCH2. In the process, Ag+ undergoes ________ A B C D E
19.
Dalton Perkin Raman Tyndall Esosteric
hydrolysis solvolysis dissociation all of the above none of the above
How many pi (π) bonds are there in H2CO? A B C D E
0 1.0 1.5 2.0 none of the above 5
SECTION B
(60 Marks)
Answer three (3) of the following five (5) questions (20 marks for each question). (If there is any physical constant or data that you need in your calculation but which is not found in the question, you may denote them as “x”, “y”… etc, explain them, and indicate such clearly in your working process and answers)
1.
“Since H+ is highly acidic and since H2O undergoes protonation easily to give H3O+, it is likely that the latter would further react with H+ to give H4O2+ readily”. Examine this statement carefully by determining whether it is true or false and, if false, under what situation would the statement be valid. Explain.
2.
A mixture of acetaldehyde CH3CHO and propanal C2H5CHO under basic conditions would readily yield four products. Identify them and sketch carefully their structures.
3.
You are given the following ions, namely (a) CH3+; (b) CH2R+; (c) CHR2+; (d) CR3+. Arrange them in a descending arrangement carefully.
4.
5.
order
of
stability
and
explain
your
Sketch the Lewis structures of the following: (a)
H2SO5
(b)
HNO3
(c)
HClO3
What is the concentration of H3O+ in a 1.00 x 10-2 M NaOH solution? State clearly the assumptions, if any, you make. (Kw = 1.00 x 10-14)
END OF PAPER
6
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