NJC Organic Chem MCQ revision set

Organic Chemistry Revision Booklet (MCQ) 2023 National Junior College 1 Name: _____________________ Class: _____________ Organic Chemistry Revision Booklet (MCQ) Content Page General Properties of Organic Molecules 2 Combustion of Organic Molecules 5 Calculations involving Organic Molecules 7 Isomerism 8 Organic Reactions / Synthesis 13 Organic Reaction Mechanism 39 Hydrolysis of Organic Molecules 53 Distinguishing Test 59 Pattern Identification 61 Amino acids and Proteins 71

Organic Chemistry Revision Booklet (MCQ) 2023 National Junior College 2 General properties of organic compounds 1. Which property of benze ne may be directly attributed to the stability associated with its delocalized electrons? A It does not conduct electricity. B Its enthalpy change of formation is endothermic. C It is susceptible to attack by nucleophiles. D It tends to undergo substitution rather than addition reactions. 2. Which statement is true regarding the formation of chlorobenzene from benzene and chlorine? A A catalyst is not required for the reaction to take place. B The six carbon atoms in benzene remain sp2 hybridised throughout the reaction. C The relative molecular mass of the organic product is 35.5 greater than that of benzene. D The reaction involves an intermediate which contains 4 delocalised electrons 3. Which of the following statements best explains why t he boiling point of butanal (76 oC) is higher than that of pentane (36 oC)? A There are permanent dipole -permanent dipole interactions between butanal molecules, but not between pentane molecules. B There are hydrogen bonds between butanal molecules, but not between pentane molecules. C The butanal molecule has a larger surface area than the pentane molecule. D The covalent bonds in the butanal molecule are stronger than those in the pentane molecule. 4. Amino acids have comparatively high melting points when c ompared with other organic compounds of similar mass. Which of the following statements best explains this observation? A In the solid state, amino acids are held together by strong hydrogen bonds. B In order to melt an amino acid, strong covalent bonds are broken. C Amino acids are held together by ionic bonding. D Amino acids are held in fixed positions in a solid lattice. 5. The diagram below represents a section of a catalytic converter on the exhaust system of a car. Which statement is incorrect regarding the processes that occur in the catalytic converter? A Platinum and rhodium catalyse the redox reactions in the catalytic converter. B Carbon monoxide and nitrogen oxide react together. C Carbon monoxide and hydrocarbons react together. D Mixture X contains carbon dioxide, nitrogen and water vapour. platinum and rhodium catalyst X CO hydrocarbons NOx

Organic Chemistry Revision Booklet (MCQ) 2023 National Junior College 3 6. 7.

Organic Chemistry Revision Booklet (MCQ) 2023 National Junior College 4 8. 9. Vanillin is the key flavour compound in vanilla, and its structure is shown. How many sp2 hybridised carbons are there in a molecule of vanillin? A 5 B 6 C 7 D 8

Organic Chemistry Revision Booklet (MCQ) 2023 National Junior College 5 10. A non-cyclic organic compound has the molecular formula C3H4O2. Which combination of functional groups cannot be present in this molecule? A one alkene and one carboxylic acid group B one alkene and one ester group C one alkene and two alcohol groups D one aldehyde and one ketone group Combustion of organic molecules 11. Which line on the graph shows the relationship between the number of carbon atoms in an alkane and the number of moles of oxygen ga s needed for complete combustion of the alkane? 12. When 15 cm 3 of a gaseous hydrocarbon X were burned in 100 cm 3 of oxygen, the final gaseous mixture contained 60 cm 3 of carbon dioxide and 10 cm 3 of unreacted oxygen. [All gaseous volumes measured under identical conditions.] What is the formula of hydrocarbon X? A. C3H6 B. C4H10 C. C3H8 D. C4H8 13. What volume of CO2 will be formed when y cm 3 of a 50:50 mixture of methane and propane is completely burnt? A. 2y cm3 B. 5y/2 cm3 C. 4 cm3 D. 5 cm3 14. When 100 cm 3 of a hydrocarbon were completely burnt in an excess of oxygen, 200 cm 3 of carbon dioxide and 0.225 g of water were formed. All volumes were measured at room temperature and pressure. What is the molecular formula of the hydrocarbon? A. C2H4 B. C4H6 C. C2H6 D. C4H12 A B C D number of carbon atoms in alkene number of moles of oxygen gas No. of carbon in alkane

Organic Chemistry Revision Booklet (MCQ) 2023 National Junior College 6 15. When an unknown organic compound is burned completely in excess oxygen, 90 cm 3 of gaseous products is collected. When cooled to room temperature, the gaseous volume decreased to 50 cm 3. A further decrease of 40 cm 3 in the gaseous volume w as observed when the gaseous mixture is passed through aqueous potassium hydroxide. What is the possible identity of the organic compound? 1 CH2CH2 2 CH3CO2H 3 CH3CH2CH3 4 CH2CHCH2OH A 1 and 3 only B 1 and 4 only C 1, 2 and 4 only D 2 and 4 only

Organic Chemistry Revision Booklet (MCQ) 2023 National Junior College 7 Calculations involving Organic Molecules 16. Experiments are carried out on three compounds X, Y, and Z. CH2 CH CH2 CH3(CH2)16CO2 CH3(CH2)16CO2 CH3(CH2)16CO2 CN BrCH2CH2CH2Br X Y Z A sample of 0.01 mol of each compound is heated under reflux with 50 cm 3 of 1 mol dm−3 NaOH (in excess) until hydrolysis is complet e and any ammonia produced is expelled from solution. The excess NaOH is then titrated in each case and is found to require 20 cm3, 30 cm3 and 40 cm3 of 1 mol dm−3 HCl for neutralisation. Which sequence of compounds matches these results? 20 cm3 30 cm3 40 cm3 A X Y Z B X Z Y C Y Z X D Z Y X 17. When 0.05 mol of an organic compound M was completely combusted in excess oxygen, it produced 0.20 mol of carbon dioxide and 0.20 mol of water. When M is heated with a few drops of acidified potassiu m di chromate, the solution remained orange in colour. Which of the following could be M? A CH3CH2CH2CH3 B CH3CH2CH2CH2OH C CH3CH2CH2CHO D CH3CH2CH2COOH 18. An alkene, with a general formula of CnH2n, reacts with hot acidified potassium manganate(VII). The products of this reaction gave the following observations: test observations 2,4-dinitrophenylhydrazine Orange ppt observed Limewater No white ppt observed What is the least number of n for such an alkene? A 3 B 4 C 5 D 6 19. In the hydrogena tion of CH2=CHCH2CN using platinum catalyst, the volume of hydrogen (measured at s.t.p.) that reacts with 1 mole of the compound could be A 22.7 dm3 B 24.0 dm3 C 45.4 dm3 D 68.1 dm3

Organic Chemistry Revision Booklet (MCQ) 2023 National Junior College 8 20. 0.01 mol of compound R is refluxed with 50 cm 3 of 1 mol dm -3 aqueous NaOH and all ammonia gas evolved is expelled. The resulting solution is subsequently titrated with 1 mol dm-3 H2SO4 solution. What is the volume of H 2SO4 required for complete neutralisation of the resulting solution? A. 10 cm3 B 20 cm3 C 30 cm3 D 40 cm3 Isomerism 21. Low fat sunflower butter spreads are high in polyunsaturates, such as linoleic acid as shown below. CH3(CH2)4CH=CHCH2CH=CH(CH2)7CO2H linoleic acid On the lid of a brand of spread, it is claime d that the spread contains virtually no trans fatty acids. Which isomer does not contain a trans linkage and could be present in the spread? A B C D (H2C)4H3C C H C H CH2 H C C