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Read the following paragraph and answer the questions given below :Carbon compounds contain many elements. The element hydrogen is present to a smaller or larger extent in majority of carbon compounds. The compounds which contain carbon and hydrogen…

Q.4 (ii) Read the following paragraph and answer the questions given below :

Carbon compounds contain many elements. The element hydrogen is present to a smaller or larger extent in majority of carbon compounds. The compounds which contain carbon and hydrogen as the only two elements are called hydrocarbons. Hydrocarbons are the simplest and the fundamental organic compounds. The smallest hydrocarbon is methane (CH4), formed by combination of one carbon atom and four hydrogen atoms. We have already seen the structure of methane. Ethane is one more hydrocarbon. Its molecular formula is C2H6.

The carbon compounds having a double bond or triple bond between two carbon atoms are called unsaturated compounds. Ethene and ethyne are unsaturated hydrocarbons. The unsaturated hydrocarbons containing a carbon-carbon double bond are called ‘Alkenes’. The unsaturated hydrocarbons whose structures contain a carbon-carbon triple bond are called ‘Alkynes’. Generally the unsaturated compounds are more reactive than the saturated compounds.

(a) What is meant by hydrocarbon ? 1
(b) Name the smallest hydrocarbon. 1
(c) Define unsaturated compound. 1
(d) Differentiate between Alkene and Alkyne. 2

1 answer

Best answer

Answer: (a) A compound of carbon and hydrogen only; (b) methane (CH4); (c) a carbon compound having a double or triple bond between two carbon atoms.

(a) Hydrocarbons are compounds which contain only two elements, carbon and hydrogen. For example, methane, ethane, ethene and ethyne.

(b) Methane, CH4, is the smallest hydrocarbon: one carbon atom joined to four hydrogen atoms.

(c) An unsaturated compound is a carbon compound in which two carbon atoms are joined by a double bond or a triple bond, so it does not have the maximum possible number of hydrogen atoms. Such compounds are more reactive than saturated compounds.

(d)

AlkeneAlkyne
Contains a carbon–carbon double bond (–C=C–).Contains a carbon–carbon triple bond (–C≡C–).
General formula CnH2n; e.g. ethene, C2H4.General formula CnH2n–2; e.g. ethyne, C2H2.
Two hydrogen atoms less than the corresponding alkane.Four hydrogen atoms less than the corresponding alkane.
Doubtly AI · 25 Oct 2026 AI-verified · Oct 2026 Report
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