Form 4 Chemistry national exam 2020 with answers
The 2020 Form 4 national exam paper for Form 4 Chemistry, question by question. Take it timed like the real exam, then see the answer and explanation to every question.
- 46 questions, 100 marks
- 120 minutes
Take this paper
120 minutes, 100 marks. Multiple choice is marked for you; you mark your written answers against the marking points.
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Instructions to candidates
Write all answers on the answer booklet. Write legibly in dark blue pen only. Answer all questions as provided in the question paper.
PART A (10 MARKS)
Choose the correct answer and write it in the answer booklet (10 Marks)
- A11 mark
Which of the following organic compounds is unsaturated?
- A.Ethylcyclobutane
- B.3-ethyl-2-methyl-1-pentene
- C.2-bromobutane
- D.2-methyl-1-chlorohexane
- A21 mark
Alkanes have a general formula of:
- A.CnH2n-1
- B.CnH2n+1
- C.CnH2n+2
- D.CnH2n
- A31 mark
The oxidation number of Chromium (Cr) in potassium dichromate (K2Cr2O7) is:
- A.+2
- B.+6
- C.+3
- D.+5
- A41 mark
The Chemical reaction in which heat is released is:
- A.Exothermic
- B.Endothermic
- C.Isomeric
- D.Precipitation
- A51 mark
To which family of Organic Compound does CH3COCH2CH3 belong to:
- A.Alcohol
- B.Aldehyde
- C.Ketone
- D.Carboxylic Acid
- A61 mark
The general formula of aldehydes is:
- A.R-CHO
- B.R-OH
- C.R-COOH
- D.R-COOR
- A71 mark
Which of the following is an allotrope of Carbon:
- A.Diamond
- B.Sulphur
- C.Nitrogen
- D.aluminium
- A81 mark
Identify the Structure of methylbutanoate in the choices below:
- A.CH3COOC2H5
- B.C3H7COOCH3
- C.HCOOC3H7
- D.CH3OC4H9
- A91 mark
Which of the following is the first synthetic organic molecule?
- A.NH4CNO
- B.C4H10
- C.NH4Cl
- D.(NH2)2CO
- A101 mark
What do we call the compounds with the same molecular formula but different structures?
- A.Isotopes
- B.Allotropes
- C.Isomers
- D.Homologous series
PART B: (10 MARKS)
Choose the correct answer for each of the blanks below and write it in the answer booklet
- B12 marks
The general formula of alkenes is _____
- B22 marks
Organics acids are also known as _____
- B32 marks
The functional group of alcohol is called _____
- B42 marks
The combustion reaction of organic compounds produces water _____ and energy.
- B52 marks
The organic compounds that contain only carbon and hydrogen atoms are called _____
PART C: (80 MARKS)
Answer the following Questions in the answer booklet.
- 1a1 mark
Define the term "Allotropes"
- 1b3 marks
State the three Allotropes of Carbon?
- 23 marks
Write down the balanced chemical equation for the hydrogenation of ethene to ethane
- 3a2 marks
Differentiate between the following pairs: Secondary alcohol and tertiary alcohol
- 3b2 marks
Differentiate between the following pairs: Carbonyl group and carboxyl group
- 3c2 marks
Differentiate between the following pairs: An aldehyde and ketone
- 42 marks
What was the first organic compound to be prepared in the laboratory?
- 55 marks
At a given temperature, the reaction CO(g) + H2O(g) <=> H2(g) + CO2(g) produces the following concentrations at an equilibrium of: [CO] = 0.200 M; [H2O] = 0.500 M; [H2] = 0.320 M; [CO2] = 0.420 M. Find K.
- 61 mark
What do we mean by the term aromatic compounds?
- 74 marks
Write down the molecular formula for the following hydrocarbons: pentane, pentene, pentyne, 1, 2-dibromobenzene
- 82 marks
Explain why are enzymes referred to as catalysts?
- 94 marks
Name the following organic compounds: (i) CH3-CH2-CH3; (ii) CH3-CH2-CH2-CH=CH2; (iii) CH3-CH2-CH(CH3)-CH2-CH(CH2-CH3)-CH2-CH2-CH3; (iv) H3C-CH=CH-CH(CH3)-CH2-CH2-CH3
- 102 marks
Explain why the oxidation number of group one elements in the periodic table is always one.
- 112 marks
Give the name of the following structure: CH3-C≡C-CH(CH3)-CH2-CH3
- 124 marks
Draw the structural formula for the following hydrocarbons: Ethene, 2-Butyne, 4-methyl-2-hexyne, 5-ethyl-3-octyne
- 132 marks
State the chemical equation for hydrogenation of propene to form propane
- 144 marks
Classify the following molecules into saturated and Unsaturated: Pentene, Hexane, Butene, Heptyne
- 152 marks
In the equation below, show the oxidizing and reducing agents: 4Al(s) + 3O2(g) -> 2Al2O3(s)
- 162 marks
Distinguish between endothermic and exothermic reactions.
- 174 marks
Categorize the following into endothermic and exothermic reactions: Melting of ice cream, Burning of a paper, Oxidation of carbohydrates in the body, Combustion of fuel
- 181 mark
Balance the following chemical equation: N2(g) + H2 -> NH3(g)
- 193 marks
Using Boyles law describe the relationship between volume and pressure.
- 202 marks
Draw the condensation reaction of two glucose molecules to produce a maltose.
- 211 mark
Define the term "molecular weight".
- 222 marks
Explain why Aldehydes and ketones are called carbonyl compounds?
- 232 marks
Why is the oxidation state of an atom in the halogen family -1?
- 244 marks
Calculate the reaction rate of A(g) + B(g) +C(g) + D(g), given the initial concentrations [A] = 0.10 M and [B] = 0.20 M, and given the reaction constant, k = 0.015 L/mol·s.
- 252 marks
Describe the process required to convert liquid into gas?
- 263 marks
Define the following terms: Oxidizing agent, Hybridization, Isomer
- 274 marks
State the chemical reactions that alkanes undergo.
- 283 marks
Write the common element that compose hydrocarbons.
Paper set by the Federal Ministry of Education, Culture and Higher Education (MoECHE), Somalia. Shared free of charge to help students prepare. The answers and explanations are written by Sheerxirfad teachers.
