Carbon and its Compounds

2026Long answer·5 marks·Q29(A)Homologous series

(i) Carbon cannot form C^4+ cation and C^4- anion. Explain. (ii) Define homologous series of carbon compounds. Why are the melting and boiling points of C_4H_{10} higher than C_3H_8 or C_2H_6? (iii) What happens when ethanol is heated with acidified potassium dichromate?

2026Long answer·5 marks·Q29(B)Naming carbon compounds

(i) How would you name the following: I. CH_3-CH_2-C(=O)H (i.e. CH_3-CH_2-CHO); II. CH_3-C≡CH. (ii) When ethanol reacts with ethanoic acid in the presence of conc. H_2SO_4, a substance with sweet smell is produced. Answer the following: I. State the class of compounds to which the sweet smelling compounds belong. II. Write the chemical equation for the reaction. (iii) Why soaps do not produce foam with hard water?

2026Assertion-Reason·1 mark·Q24Ethanol and ethanoic acid

Assertion (A): Pure ethanoic acid is also known as glacial acetic acid. Reason (R): Pure ethanoic acid often freezes during winter due to its low melting point of 290 K.

1. (a) Both Assertion
2. (b) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
3. (c) Both Assertion
4. (d) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
5. (e) Assertion
6. (f) is true, but Reason (R) is false.
7. (g) Assertion
8. (h) is false, but Reason (R) is true.

2026MCQ·1 mark·Q20Soaps and detergents

While washing dirty clothes by soap, micelles are formed. Select the correct statement about micelles.

1. (a) The hydrophobic tail of the soap molecule is in the interior of the cluster, whereas hydrophilic end is on the surface of the cluster.
2. (b) The hydrophobic tail is on the surface of the cluster, whereas hydrophilic end is in the interior of cluster.
3. (c) Both hydrophobic tail and hydrophilic end are in the interior of the cluster.
4. (d) Both hydrophobic tail and hydrophilic end are on the surface of the cluster.

2025Long answer·5 marks·Q34(a)Naming carbon compounds

(i) Draw two isomeric structures of Butene (C_4H_8). (ii) Name the following compounds: (I) CH_3-CH_2-CH_2-Cl (a chain of three carbons each fully H-saturated with a Cl on the end carbon); (II) CH_3-CH_2-CO-CH_3 (a four-carbon chain with a C=O double bond on the third carbon). (iii) Write the chemical equations for the following reactions. Mention one essential condition each for these reactions to take place. (I) Ethanol undergoes complete oxidation (II) Propene undergoes hydrogenation (III) Ethanoic acid reacts with ethanol.

2025Long answer·5 marks·Q34(b)Ethanol and ethanoic acid

(i) A carbon compound X is a good solvent. On reaction with sodium, X forms two products Y and Z. Z is used to convert vegetable oil into vegetable ghee. Identify and name X, Y and Z. Also write the equation of reaction of X with sodium to justify your answer. (ii) Write chemical equation to show what happens when ethanol: (I) burns in oxygen/air. (II) is heated at 443 K in excess conc. H_2SO_4. (III) reacts with acidified potassium dichromate.

2024MCQ·1 mark·Q4Covalent bonding in carbon

Carbon compounds: (i) are good conductors of electricity. (ii) are bad conductors of electricity. (iii) have strong forces of attraction between their molecules. (iv) have weak forces of attraction between their molecules. The correct statements are:

1. (a) (i) and (ii)
2. (b) (ii) and (iii)
3. (c) (ii) and (iv)
4. (d) (i) and (iii)

2024Long answer·5 marks·Q34(a)Homologous series

(i) Define a homologous series of carbon compounds. (ii) Why is the melting and boiling points of C_4H_8 higher than that of C_3H_6 or C_2H_4? (iii) Why do we NOT see any gradation in chemical properties of a homologous series compounds? (iv) Write the name and structures of (i) aldehyde and (ii) ketone with molecular form C_3H_6O.

2024Long answer·5 marks·Q34(b)Ethanol and ethanoic acid

(i) Write the name and structure of an organic compound 'X' having two carbon atoms in its molecule and its name is suffixed with '-ol'. (ii) What happens when 'X' is heated with excess concentrated sulphuric acid at 443 K? Write chemical equation stating the conditions for the reaction. Also state the role played by concentrated sulphuric acid in the reaction. (iii) Name and draw the electron dot structure of hydrocarbon produced in the above reaction.

2023MCQ·1 mark·Q7Covalent bonding in carbon

Consider the structures of the three cyclic carbon compounds A, B and C given below and select the correct option from the following:

1. (a) A and C are isomers of hexane and B is benzene.
2. (b) A is an isomer of hexane, B is benzene and C is an isomer of hexene.
3. (c) A is a saturated cyclic hydrocarbon and B and C are unsaturated cyclic hydrocarbons.
4. (d) A is cyclohexane and B and C are the isomers of benzene. [A is a six-membered ring with each carbon bonded to two hydrogens (cyclohexane); B and C are six-membered rings with alternate double bonds and one hydrogen per carbon (benzene / Kekule structures).]

2023Long answer·5 marks·Q34(a)Ethanol and ethanoic acid

A saturated organic compound 'A' belongs to the homologous series of alcohols. On heating 'A' with concentrated sulphuric acid at 443 K, it forms an unsaturated compound 'B' with molecular mass 28 u. The compound 'B' on addition of one mole of hydrogen in the presence of Nickel, changes to a saturated hydrocarbon 'C'. (i) Identify A, B and C. (ii) Write the chemical equations showing the conversion of A into B. (iii) What happens when compound C undergoes combustion? (iv) State one industrial application of hydrogenation reaction. (v) Name the products formed when compound A reacts with sodium.

2023Long answer·5 marks·Q34(b)Soaps and detergents

(i) With the help of diagram, show the formation of micelles, when soap is applied on oily dirt. (ii) Take two test tubes X and Y with 10 mL of hard water in each. In test tube 'X', add few drops of soap solution and in test tube 'Y' add a few drops of detergent solution. Shake both the test tubes for the same period. (1) In which test tube the formation of foam will be more? Why? (2) In which test tube is a curdy solid formed? Why?

2022Very short answer·2 marks·Q1Covalent bonding in carbon

(a) Write the molecular formula of the following carbon compounds: (i) Methane (ii) Propane. (b) Carbon compounds have low melting and boiling points. Why?

2022Short answer·3 marks·Q9(b)Covalent bonding in carbon

(i) Write the molecular formula of benzene and draw its structure. (ii) Write the number of single and double covalent bonds present in a molecule of benzene. (iii) Which compounds are called alkynes?

2022Short answer·3 marks·Q9(a)Saturated and unsaturated hydrocarbons

Draw two different possible structures of a saturated hydrocarbon having four carbon atoms in its molecule. What are these two structures of the hydrocarbon having same molecular formula called? Write the molecular formula and the common name of this compound. Also write the molecular formula of its alkyne.