alleryStart learning →What type of carbon-carbon bonds are found in alkanes?
- Double bonds
- Triple bonds
- Ionic bonds
- Single bonds
Show answer and solution
Correct answer: D. Single bonds
Alkanes are saturated hydrocarbons whose carbon atoms are linked by single bonds.
ICSE Class 10 Organic Chemistry: introduction and hydrocarbons — practice questions
Explore 51 free Organic Chemistry: introduction and hydrocarbons questions in ICSE Class 10 Chemistry. Open each question or exercise to read its content, reference answers and available explanation.
Practise Organic Chemistry: introduction and hydrocarbons with Quill →Organic Chemistry: Introduction and Hydrocarbons: quick revision
Begin with the carbon skeleton and the bonds between carbon atoms. These original revision examples connect open-chain alkane, alkene and alkyne formulas with simple names and structural isomers. Check the family and its conditions before applying a formula; the molecular formula alone may not identify a unique structure.
Key ideas and when to use them
- Open-chain alkanes with only single bonds have the general formula $C_nH_{2n+2}$. Carbon forms four bonds in these structures.
- Open-chain hydrocarbons with exactly one carbon-carbon double bond and no rings have the formula $C_nH_{2n}$ for n ≥ 2.
- Open-chain hydrocarbons with exactly one carbon-carbon triple bond and no other multiple bonds have the formula $C_nH_{2n-2}$ for n ≥ 2.
- For these simple families, use -ane, -ene and -yne for single, double and triple bonds respectively. A homologous series has the same functional group and successive members differ by $CH_2$.
Common mistakes
- Do not apply an open-chain formula to every cyclic compound. An alkene and a cycloalkane can share a molecular formula.
- A longer-looking drawing is not always a different molecule. Trace the carbon connections before counting structural isomers.
- Use the correct bond family before naming the compound. Ethane, ethene and ethyne are different molecules.
- Number a simple alkene or alkyne chain from the end nearer the multiple bond.
Three worked examples
Example 1: An open-chain hydrocarbon has five carbon atoms, one double bond and no other multiple bonds. What is its molecular formula?
- The stated conditions put the compound in the monoalkene family.
- Use $C_nH_{2n}$ with n = 5: the hydrogen count is 10.
$C_5H_{10}$.
Example 2: Name the open-chain molecule $CH_3-CH_2-C\equiv CH$.
- The main chain contains four carbon atoms, so the parent begins with but-.
- Number from the triple-bond end. The triple bond starts at carbon 1, and the suffix is -yne.
But-1-yne (also written 1-butyne).
Example 3: How many constitutional isomers does the alkane $C_4H_{10}$ have?
- A chain of four carbons gives butane.
- A chain of three with one methyl branch on its middle carbon gives 2-methylpropane. Moving the branch to an end recreates the straight chain.
Two: butane and 2-methylpropane.
Qallery AI-assisted study notes and original examples. Further reading: OpenStax Chemistry 2e: Hydrocarbons.
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Practise Organic Chemistry: introduction and hydrocarbons →Organic Chemistry: introduction and hydrocarbons questions and exercises with answers
Showing questions 1–30 of 51.
What type of carbon-carbon bonds are found in alkanes?Read the answer and worked solution →Which general formula describes acyclic alkanes?Read the answer and worked solution →Which hydrocarbon class has a C=C bond?Read the answer and worked solution →Which multiple bond is present in an alkyne?Read the answer and worked solution →Which formula applies to an acyclic alkene with one double bond?Read the answer and worked solution →For a simple acyclic alkyne, which formula gives its hydrogen count?Read the answer and worked solution →Which suffix pair names single- then double-bond hydrocarbons?Read the answer and worked solution →What is the IUPAC name for CH₄?Read the answer and worked solution →How is the two-carbon saturated hydrocarbon named?Read the answer and worked solution →How many structural isomers does butane, C₄H₁₀, have?Read the answer and worked solution →What distinguishes members of a homologous series?Read the answer and worked solution →By what unit do successive straight-chain alkanes differ?Read the answer and worked solution →What is the mass difference between adjacent alkane homologues?Read the answer and worked solution →Which properties are generally similar within a homologous series?Read the answer and worked solution →What is true of molecules that are isomers?Read the answer and worked solution →How do structural isomers differ?Read the answer and worked solution →What do cis and trans describe around an alkene double bond?Read the answer and worked solution →Why do cis and trans alkene forms interconvert slowly?Read the answer and worked solution →How is the main chain chosen when naming an alkane?Read the answer and worked solution →How are branched alkane substituents located in the name?Read the answer and worked solution →What determines the number used for a substituent position?Read the answer and worked solution →What prefix names a cyclic alkane?Read the answer and worked solution →What is acetylene called in IUPAC nomenclature?Read the answer and worked solution →Which substances are the two main commercial sources of alkanes?Read the answer and worked solution →What is an alkyl group?Read the answer and worked solution →Which feature is used to distinguish position isomers?Read the answer and worked solution →Which bond types occur in a carbon-carbon double bond?Read the answer and worked solution →What does carbon's catenation mean?Read the answer and worked solution →What is the valency of carbon in organic compounds?Read the answer and worked solution →How does carbon usually attain a filled outer shell?Read the answer and worked solution →
Worked practice questions
Which general formula describes acyclic alkanes?
- CₙHₙ
- CₙH₂ₙ₋₂
- CₙH₂ₙ₊₂
- CₙH₂ₙ
Show answer and solution
Correct answer: C. CₙH₂ₙ₊₂
Acyclic alkanes follow the formula CₙH₂ₙ₊₂.
Which hydrocarbon class has a C=C bond?
- Alkane
- Alkyne
- Alkene
- Alcohol
Show answer and solution
Correct answer: C. Alkene
1. The symbol C=C represents a double bond between two carbon atoms. A hydrocarbon contains only carbon and hydrogen.
2. Alkenes are the hydrocarbon family characterised by a carbon-carbon double bond. Alkanes have only single carbon-carbon bonds, while alkynes contain a carbon-carbon triple bond.
3. Therefore Alkene, option C, is correct. An alcohol contains oxygen in a hydroxyl group, so it is not a hydrocarbon family.
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