carbon and its compound important question

Carbon and its Compounds Class 10 Notes Science Chapter 4

carbon and its important pdf questions 

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Question.2 What is the difference in the molecular formula of any two consecutive members of a homologous series of organic compounds?
Answer. —CH₂— is the difference in the molecular formula of any two consecutive members of a homologous series of organic compounds.

Question.3 very very important
(a) Give a chemical test to distinguish between saturated and unsaturated  hydrocarbons.
(b) (i) Name the products formed when ethanol burns in air. ‘
(ii) What two forms of energy are liberated on burning alcohol?
(c) Why is the reaction between methane and chlorine considered a substitution
reaction?
Answer.

Question.4
(a) Why are covalent compounds generally poor conductors of electricity?
(b) Name the following compound:

(c) Name the gas evolved when ethanoic acid is added to sodium carbonate. How would you prove the presence of this gas?
Answer.

Question.5 Name the carbon compound which on heating with excess of concentrated sulphuric acid at 443 K gives ethene.
Answer.

Question.6 What is meant by a sturated hydrocarbon?
Answer. Those hydrocarbons in w hich valency of carbon is satisfied by single bonds only are called sturated hydrocarbons.

Question.7 Name the compound formed when ethanol is warmed with ethanoic acid in the
presence of a few drops of cone.H₂S₀₄
Answer.

Question.8 Draw the structure of CH₃COOH molecule.
Answer.

Question.9 Draw the structure of ethanol molecule.
Answer.

Question.10 What happens when a small piece of sodium is dropped into ethanol? 
Answer. Hydrogen gas will be evolved.

Question.11 What is meant by a functional group in an organic compound? Name the functional group present in
(i) CH₃CH₂OH
(ii) CH₃COOH
Answer.
(a) Functional group is an atom or group of atoms or reactive part of compound, which determines chemical properties of compounds.
(i) —OH (Alcohol)
(ii) —COOH (Carboxylic acid)
Question.12 Give reasons for the following observations:
(a) The element carbon forms a very large number of compounds.
Answer.
(a) Carbon forms large number of compounds since carbon is small in size and can form stable covalent bonds (catenation) and it shows tetravalency.
Question.13 What is ethanoic acid? Write the formula of the functional group present in this acid.
What special name is given to its 5 – 8% solution in water? How does ethanoic acid react with sodium carbonate? Write a chemical equation of the reaction and common name of the salt produced.
Answer.

Question.14 State two characteristic features of carbon which when put together give rise to large
number of carbon compounds.
Answer. (i) Catenation (ii) Tetravalency of carbon

Question.15 Write the structural formula of chloroethane.
Answer.

Question.16 Write the name and molecular formula of an organic compound having its name suffixed with ‘-ol and having two carbon atoms in the molecule. With the help of a
balanced chemical equation indicate what happens when it is heated with excess of r cone.H₂So_4.
Answer.

Question.17 Write the names and molecular formula of two organic compounds having functional r group suffixed as ‘-oic acid’. With the help of a balanced chemical equation and explain what happens when any one of them reacts with sodium hydroxide.
Answer.

Question.18 What is a homologous series? Which two of the following organic compounds belong
to the same homologous? 
CH₃ ,C₂H₆, C₂H₆O, C₂H₆O_2,CH₄O     
Answer.      

Question.21 An organic compound ‘A’ is an essential constituent of wine and beer. Oxidation of ‘A’ yields an organic acid ‘B’ which is present in vinegar. Name the compounds ‘A’ and ‘B’ and write their structural formula. What happens when ‘A’ and ‘B’ react in the presence of an acid catalyst? Write the chemical equation for the reaction.
Answer.

Question.22 What is ethanol? State its two properties. What happens when it is heated with excess of cone. H₂SO₄ at 443 K? What role does cone. H₂SO₄ play in this reaction? Write chemical equation of the reaction involved and the structural formula of the main product formed.
Answer.

Question.24 How many covalent bonds are there in a molecule of ethane (C₂H₆)?
Answer. There are 7 covalent bonds in a molecule of ethane.

Question.25 Write the electron dot structure of ethene molecule (C₂H₄).
Answer.

Question.26 Write the electron dot structure of ethane molecule (C₂H₆).
Answer.

Question.27 Draw the structure of butanone molecule, CH₃COC₂H₅.
Answer.

Question.28 Draw the structure of the hexanal molecule, C₅H₁₁CHO.
Answer.

Question.29 Butanone is a four carbon per molecule compound. Name the functional group present in it.
Answer. Ketone

Question.30 Name the following compound:

Answer. 1-Hexyne is IUPAC name of the compound.

Question.31 What is an ‘esterification’ reaction? Describe an activity to show esterification. Very IMPORTANT
Answer.

Question.32 Out of HCI and CH₃COOH, which one is a weak acid and why? Describe an activity to
support your answer.
Answer. Acetic acid ( CH₃COOH) is a weaker acid because it does not dissociate completely into its ions in aqueous solution.
Activity: Add zinc metal in HCI and CH₃COOH respectively. The hydrogen gas will be evolved faster in HCI and slowly in CH₃COOH. It shows acetic acid is a weak acid.
Alternative Method:
If we use pH paper, the colour of pH paper will be dark red in HCI and light red in CH₃COOH which shows HCI is a strong acid and CH₃COOH is a weak acid.

IMP

Question.33Write chemical equations for what happens when
(i) sodium metal is added to ethanoic acid.
(ii) solid sodium carbonate is added to ethanoic acid.
(iii) ethanoic acid reacts with a dilute solution of sodium hydroxide.
Answer.

Question.34 Describe two examples of different oxidations of ethanol. Name the products obtained in each case.
Answer.

Question.36 (a) In tabular form, differentiate between ethanol and ethanoic acid under the following heads:
(i) Physical state (ii) Taste
(iii) NaHCO₃ test (iV) Ester test
(b) Write a chemical reaction to show the dehydration of ethanol.
Answer. 

Question.37 (a) State two properties of carbon which lead to a very large number of carbon compounds.
Answer.
(a) (i)-Catenation (ii) Tetravalency
Question.38 Explain isomerism. State any four characteristics of isomers. Draw the structures of possible isomers of butane, C₄H₁₀
Answer. Isomerism is a phenomenon due to which some compounds have same molecular formula but different structural formulae.
Characteristics:
(i) They differ in structural formula.
(ii) They differ in melting point.
(iii) They differ in boiling point.
(iv) They differ in solubility in same solvent.

Question.39 Give reasons for the following:
(i)Element carbon forms compounds mainly by covalent bonding.
(ii)Diamond has a high melting point.
(iii)Graphite is a good conductor of electricity.
(iv)Acetylene bums with a sooty flame.
(v)Kerosene does not decolourise bromine water while cooking oils do.
Answer.
(i) It is because carbon has four valence electrons, it cannot gain or lose four electrons because high energy is needed. It can only share four electrons.
(ii) It is due to strong covalent bonds and compact structure of diamond.
(iii) It is due to presence of free electrons in graphite because each carbon is linked to three more carbon atoms.
(iv) It is due to high percentage of carbon, it burns with sooty or smoky flame.
(v) Kerosene oil is mixture of saturated hydrocarbons therefore does not decolourise bromine water.

Question.40 Name the functional group present in each of the following organic compounds:
(i) C₂H₅CI
(ii) C₂H₅OH
Answer.
(i) (—Cl) Halogen (Chloro)
(ii) (—OH) Alcohol

Question.47 Write the name and formula of the 2nd member of the series of carbon compounds whose general formula is CnH_2n.
Answer.
C₃H_6, H₂C=CH—CH₃
Propene is second member of series whose general formula is C_nH_2n.

Question.48 What are isomers? Draw the structures of two isomers of butane, C₄H₁₀. Why can’t we have isomers of first three members of alkane series?
Answer. Those compounds, which have same molecular formula but different structural formulae are called isomers.

In first three members of alkane series, branching is not possible. Therefore, we cannot have isomers.

Question.49 Define homologous series of organic compounds. List its two characteristics. Write the name and formula of the first member of the series of alkenes.
Answer. The series of organic compounds having same functional group and similar chemical properties is called homologous series.
Each member differs from successive member by —CH₂— group. The difference in molecular weight between two successive members is 14 u.
Characteristics:
(i) It has same general formula, from which, all members can be derived.
(ii) They have similar chemical properties.
C₂H₄, CH₂=CH₂, Ethene is first member of alkene series.

Question.50 Complete the following equations:

Answer.

Question.51 Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their
(i) physical properties, and (ii) chemical properties.
Answer. The series consists of members of same family with similar physical and chemical properties, therefore, called homologous series
(i) CH₃OH, and (ii) CH₃CH₂OH are two consecutive members of homologous series.
Alkyl group —CH₃ and —CH₃CH₂ part determines physical properties. Functional group —OH determines chemical properties of the compounds.

Question.52 Name the oxidising agent used for the conversion of ethanol to ethanoic acid. Distinguish between ethanol and ethanoic acid on the basis of (i) litmus test, (ii) reaction with sodium hydrogencarbonate.
Answer. Alkaline potassium permanganate or Acidified potassium dichromate.
(i)Ethanol will not affect litmus paper. Ethanoic acid will turn blue litmus ‘ paper red.
(ii) Ethanol will not react with sodium hydrogen carbonate. Ethanoic acid will give brisk effervescence due to colourless, odourless carbon dioxide gas.

Question.53 Distinguish between esterification and saponification reactions of organic compounds with the help of the chemical equation for each. What is the use of (i) esters and (ii) saponification process?
Answer.

Question.55 List in tabular form three physical and two chemical properties on the basis of which ethanol and ethanoic acid can be differentiated
Answer.

Question.56 What are the hydrocorbons write the name and general formula of (i) sturated hydrocarbons, (ii) unsaturated hydrocarbons, and draw the structure of one hydrocarbon of each type. How can an unsaturated hydrocarbon be made saturated?
Answer.