Organic Chemistry

Chemistry, SSC-KPK Class 10. This chapter is split into 37 topics and has 890 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Identifying an alkane from its relative molecular mass 26 questions
2. Characteristics of organic compounds I 25 questions
3. Exercise: multiple-choice items 22 questions
4. Early classification into inorganic and organic substances 22 questions
5. Alkyl groups with larger carbon numbers 24 questions
6. Sources of organic compounds: fossil fuels and coal 22 questions
7. Molecular formula of an alkane from its carbon number 28 questions
8. Relative molecular mass of alkanes and alkyl groups 28 questions
9. Identifying the class of a compound from its formula I 28 questions
10. Cyclic alkanes 22 questions
11. Definition of organic compounds and organic chemistry 23 questions
12. Functional groups: the concept 26 questions
13. Rules for naming alkanes 25 questions
14. Functional groups by the elements they contain 21 questions
15. Difference between an alkane and an alkyl radical 23 questions
16. The seven homologous series of organic compounds 20 questions
17. Alkanes: saturated hydrocarbons and general formula 23 questions
18. Alkyl radicals and their formulae 25 questions
19. Carbon number of an alkane from its hydrogen number 26 questions
20. Petroleum 22 questions
21. Characteristics of organic compounds II 24 questions
22. Deducing the alkane formula from bond counts 24 questions
23. Classifying compounds as organic or inorganic 26 questions
24. Counting bonds in straight chain alkanes 28 questions
25. Comparison of organic and inorganic compounds 20 questions
26. Activities of Unit 11 and key points 21 questions
27. Classification of alkanes: open chain cyclic straight and branched 24 questions
28. Natural gas plants and laboratory synthesis as sources 21 questions
29. Next homologue of a compound 28 questions
30. Exercise: short and long questions 22 questions
31. Classes of organic compounds in Table 11.2 28 questions
32. Identifying the class of a compound from its formula II 24 questions
33. Homologous series: definition and properties 23 questions
34. Uses of organic compounds 22 questions
35. Finding the carbon number from the number of bonds 24 questions
36. Previous homologue and nth member of a series 24 questions
37. Society Technology Science: vital force theory and Wohler 26 questions

Sample questions: Organic Chemistry

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. Why does the source-based classification no longer define organic compounds today?

• A. All organic compounds are now obtained from rocks
• B. Organic compounds no longer contain carbon
• C. Inorganic compounds are now obtained only from plants
• D. Organic compounds can be made in the laboratory from inorganic substances(correct answer)

Answer: D.The synthesis of urea by Wohler showed living organisms are not required to make organic compounds; organic compounds are now defined as compounds of carbon.

Q2. Reactions of organic compounds are slow because they generally involve

• A. free ions that react instantly (standard reasoning)
• B. metals reacting with water (standard reasoning)
• C. covalent bonds that must be broken (standard reasoning)(correct answer)
• D. fast electron transfer between ions (standard reasoning)

Answer: C.Covalent bonds have to be broken in molecular reactions, unlike ionic reactions in solution (standard explanation; the book states only that organic reactions are slower).

Q3. Exercise Q3(iv) asks how organic and inorganic compounds differ. Which statement is a correct difference?

From your book: see this page (page 35) Full page Open book

From your book: see this page (page 36) Full page Open book

• A. Organic compounds are generally ionic, inorganic compounds are always covalent
• B. Organic compounds are generally covalent, inorganic compounds are often ionic(correct answer)
• C. Organic compounds never burn, inorganic compounds always burn
• D. Organic compounds always conduct electricity, inorganic compounds never do

Answer: B.Characteristic 5 of the book gives this fact: the correct answer is Organic compounds are generally covalent, inorganic compounds are often ionic.

Q4. How does a functional group differ from an alkyl group?

• A. A functional group is ionic, while an alkyl group is covalent
• B. A functional group replaces a hydrogen atom of the alkane and gives characteristic properties, while an alkyl group is derived from the alkane by removing one hydrogen(correct answer)
• C. A functional group is always derived from an alkane by removing a hydrogen atom, while an alkyl group replaces one
• D. A functional group contains no atoms, while an alkyl group contains atoms

Answer: B.Key points 6 and 7 of the book gives this fact: the correct answer is A functional group replaces a hydrogen atom of the alkane and gives characteristic properties, while an alkyl group is derived from the alkane by removing one hydrogen.

Q5. Which functional groups contain carbon, hydrogen and oxygen, according to Section 11.5.1?

• A. Alcohols, aldehydes, ketones and carboxylic acids(correct answer)
• B. Alkanes and hydrocarbons only, as they have C and H
• C. Amines and alkyl halides only, as they have N or X
• D. Alkyl halides and alkanes only, as they have X or H

Answer: A.Section 11.5.1: functional groups containing carbon, hydrogen and oxygen: aldehydes, ketones and carboxylic acids are its examples; alcohols too.

Q6. Homologues in a series have a general formula and show

• A. identical physical properties (standard knowledge)
• B. a regular gradation in physical properties(correct answer)
• C. random properties (standard knowledge)
• D. no relation in properties (standard knowledge)

Answer: B.Physical properties such as melting and boiling points change gradually along the series (standard knowledge; the book states same chemical properties).

Q7. Which of the following pairs of compounds do NOT belong to the same homologous series?

• A. C₂H₅OH and C₂H₅COOH(correct answer)
• B. CH₃COOH and C₂H₅COOH
• C. CH₃OH and C₂H₅OH
• D. CH₄ and C₂H₆

Answer: A.An alcohol and a carboxylic acid have different functional groups. This is exercise Q1(xi): C₂H₅COOH has different chemical properties among the alcohols.

Q8. The seven series listed in the book are

• A. hydrocarbons, alcohols, carboxylic acids, carbonyl compounds, alkyl halides, amines and ethers(correct answer)
• B. hydrocarbons, acids, bases, salts, oxides, sulphates and ethers
• C. alcohols, phenols, ethers, amides, nitriles, esters and imides
• D. alkanes, alkyl, alkenes, alkynes, aldehydes, ketones and esters

Answer: A.Section 11.6 of the book gives this fact: the correct answer is hydrocarbons, alcohols, carboxylic acids, carbonyl compounds, alkyl halides, amines and ethers.

Q9. The compound NaCN is classified as

• A. an organic acid
• B. an inorganic compound(correct answer)
• C. an organic compound (a hydrocarbon)
• D. a hydrocarbon derivative

Answer: B.NaCN is classed with metal cyanides (as in the book's exercise), which the book excludes from the organic compounds (or it contains no carbon), so it is inorganic.

Q10. Long question Q3(iii) asks about

• A. the manufacture of nitric acid from the air
• B. the history of the periodic table and its families
• C. the neutralisation of acids by bases in solution
• D. the characteristic properties of organic compounds and why they are placed in a separate branch of chemistry(correct answer)

Answer: D.Exercise Q3(iii) of the book gives this fact: the correct answer is the characteristic properties of organic compounds and why they are placed in a separate branch of chemistry.