CBSE Class 10 Science — Carbon and its Compounds

Which of the following set of compounds does not belong to same homologous series?

The formula of functional group for aldehyde is:

Which of the following will not undergo addition reaction?

Directions: For question number 24, two statements are given, one labelled as Assertion (A) and the other is labelled as Reason (R). Select the correct answer from the codes given below. Assertion (A): Carbon shares its valence electrons with other atoms of carbon or with atoms of other elements. Reason (R): The shared electrons belong to the outermost shells of both the atoms and lead to both atoms attaining the noble gas configuration.

Alcohol forms a homologous series with general formula $C_nH_{2n + 1} - OH$ and -OH group as functional group. Ethanol is commonly called alcohol and is used in alcoholic drinks. It is good solvent, used in medicines, cough syrups, tonics etc. (a) Write structural formula and name of 4th member of alcohol homologous series. (b) What happens when ethanol is heated with alkaline $KMnO_4$? Write chemical equation involved. (c) Write the chemical equation of reaction of ethanol with ethanoic acid in the presence of concentrated $H_2SO_4$. Write the name of this reaction. OR (c) What happens when ethanol is heated with excess concentrated sulphuric acid at $443 K$? Write chemical equation involved. What is the role of concentrated sulphuric acid in this reaction?

Alcohol forms a homologous series with general formula $C_nH_{2n+1}-OH$ and -OH group as functional group. Ethanol is commonly called alcohol and is used in alcoholic drinks. It is a good solvent, used in medicines, cough syrups, tonics etc. (a) Write structural formula and name of 4th member of alcohol homologous series. (b) What happens when ethanol is heated with alkaline $KMnO_4$? Write chemical equation involved. (c) Write the chemical equation of reaction of ethanol with ethanoic acid in the presence of concentrated $H_2SO_4$. Write the name of this reaction. OR (c) What happens when ethanol is heated with excess concentrated sulphuric acid at 443 K? Write chemical equation involved. What is the role of concentrated sulphuric acid in this reaction?

(a) (i) Give reasons for the following: (I) Covalent compounds are poor conductor of electricity. (II) Soap does not form lather in hard water. (III) Carbon shows catenation but silicon does not. (ii) Write chemical equations for the following: (I) Oxidation of ethanol by acidified $\mathrm{K}_2\mathrm{Cr}_2\mathrm{O}_7$ (II) Hydrogenation of ethene. OR (b) Mohan heated ethanol with a compound 'X' in the presence of a few drops of conc. $\mathrm{H}_2\mathrm{SO}_4$ and observed a sweet smelling compound 'Y' is formed. When 'Y' is treated with sodium hydroxide it gives back ethanol and a compound 'Z'. (i) Identify 'X', 'Y' and 'Z'. (ii) Write the role of conc. $\mathrm{H}_2\mathrm{SO}_4$ in the reaction. (iii) Write the chemical equations involved and name the reactions.

Select from the following a hydrocarbon having one $C-C$ bond and one $C=C$ bond :

Given below are the structures of some hydrocarbons. Select the two structures which are related to each other from the given options : (i) H-C-C-C=C-H (with H substituents) (ii) H-C-C-C-C-H (with H substituents) (iii) H-C-C-C-H (cyclic/branched structure with H substituents) (iv) Cl-C-C-C=C-H (with H substituents)

A Hydrocarbon which does not belong to the same homologous series of carbon compounds is:

Choose the incorrect statement about the common reaction used in hydrogenation of vegetable oils.

If we make carbon skeleton with four carbon atoms, the two different possible skeletons will be

Assertion (A): Carbon and its compounds are our major sources of fuels. Reason (R): Most of the carbon compounds on burning release a large amount of heat and light.

(a) Select from the following the members of same homologous series: [structures shown in the accompanying diagram] (b) What happens to (i) the melting point, and (ii) the solubility of compounds as the molecular mass of the compounds in a homologous series increases?

(a) (i) Draw two isomeric structures of Butene $(C_4H_8)$. (ii) Name the following compounds (structural formulas of chloropropane isomers given). (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 OR (b) (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.

(a) (i) A compound 'X' having two carbon atoms in its molecule turns blue litmus red and $5-8\%$ solution of 'X' in water is widely used as a preservative. Identify the compound 'X' and write its structure. (ii) Compare its pH nature with a mineral acid. (iii) 'X' on reacting with alcohols produces sweet smelling compounds, used in making perfumes. Name the reaction and write its chemical equation. (iv) When sodium carbonate is added to 'X', a colourless gas is produced which turns lime water milky. Write the chemical equation for the reaction giving the name of the salt produced. OR (b) (i) Differentiate between saturated and unsaturated hydrocarbons by giving one example each, with a structural formula. (ii) Write the method of converting an unsaturated hydrocarbon into a saturated hydrocarbon. Name the industry where this reaction is commonly used. (iii) Write the name and structure of a hydrocarbon having double bond and four carbon atoms in its one molecule.

(a) Name an alcohol and a carboxylic acid having two carbon atoms in their structures. Draw their structures and state how this alcohol can be converted into a carboxylic acid. What happens when these two compounds react in the presence of an acid? Write chemical equations for the reactions involved in the two cases mentioned above. OR (b) What are soaps? Write the structure of a soap molecule. Explain the cleansing action of a soap. Why are soaps not considered suitable for washing clothes in a region where water is hard? How is this problem overcomed?

(A) A carbon compound 'A' on heating with excess conc. $H_2SO_4$ forms a compound 'B', which on addition of one mole of hydrogen gas in the presence of nickel catalyst forms a compound 'C'. 'C' on combustion in air forms 2 moles of carbon dioxide and 3 moles of water. Identify 'A', 'B' and 'C' and write their structures. Give chemical equations of the reactions involved. Also state the role of concentrated sulphuric acid in the formation of 'B' from 'A'. OR (B) A carbon compound 'A' is widely used as a preservative in pickles and has a molecular formula $C_2H_4O_2$. This compound reacts with ethanol to form a sweet smelling compound 'B'. (i) Identify the compound 'A' and write its structure. (ii) Write the chemical equation for the reaction of 'A' with ethanol to form compound 'B'. State the role of presence of an acid in the reaction. (iii) How can we get compound 'A' back from 'B'? (iv) How can 'A' be obtained from ethanol? (v) Name the gas produced when compound 'A' reacts with washing soda.

(A) (a) What is meant by the term homologous series of carbon compounds? Write molecular formula of any two consecutive members of homologous series of ketones. (b) Write chemical equation of the reactions of ethanoic acid with (i) Sodium hydroxide and (ii) Ethanol (in the presence of an acid); giving the name of the products in each case. (c) Draw the structure of the molecule of benzene. OR (B) (a) Write the molecular formula of ethyne and draw its electron dot structure. (b) Write chemical equation to show the reaction of ethanol with (i) Sodium metal (ii) Ethanoic acid (in the presence of an acid) (iii) Acidified potassium dichromate Write the name of the product formed in each case.

The combining capacity of various elements depends on the number of valence electrons. Also the reactivity of elements is explained as their tendency to attain a completely filled outer shell, that is, to attain a noble gas configuration. This may be either through gain of electrons or loss of electrons or sharing of electrons. (a) An element A has atomic number 16, how will it attain its nearest noble gas configuration? (b) Write the number of (i) single and (ii) double covalent bonds in a molecule of butene ($C_4H_8$). (c) (A) Explain the formation of a molecule of ammonia ($NH_3$), using electron dot structure. (Atomic number of nitrogen is 7) OR (c) (B) Why does carbon share its valence electrons with other atoms of carbon or with atoms of other elements?

The structural formula of Cyclohexane is

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 :

The number of single and double bonds present in a molecule of benzene $\mathrm{(C_6H_6)}$ respectively, are:

Which one of the following hydrocarbons is different from the others?

Consider the following statements about homologous series of carbon compounds : (a) All succeeding members differ by $-\mathrm{CH}_2$ unit. (b) Melting point and boiling point increases with increasing molecular mass. (c) The difference in molecular masses between two successive members is $16\text{ u}$. (d) $\mathrm{C}_2\mathrm{H}_2$ and $\mathrm{C}_3\mathrm{H}_4$ are NOT the successive members of alkyne series. The correct statements are -

Assertion (A): Some vegetable oils are healthy. Reason (R): Vegetable oils generally have long unsaturated carbon chains.

Distinguish between a saturated and an unsaturated hydrocarbon by flame test. List the products of combustion reaction of a saturated hydrocarbon.

The melting and boiling points of carbon compounds are generally low and they are largely non-conductors of electricity. State two conclusions based on these two properties.

Why is the conversion of ethanol to ethanoic acid an oxidation reaction? Name the oxidising agent used in this conversion. Write chemical equation for this oxidation reaction. How is this reaction different from the reaction in which ethanol burns in the presence of oxygen?

(a) (i) Give reason why carbon can neither form $\mathrm{C}^{4 + }$ cations nor $\mathrm{C}^{4 - }$ anions but form covalent compounds. (ii) What is homologous series of carbon compound ? Write the molecular formula of any two consecutive members of homologous series of aldehydes. (iii) Draw the structure of the molecule of cyclohexane $(\mathrm{C}_6\mathrm{H}_{12})$. OR (b) (i) Name a commercially important carbon compound having functional group -OH and write its molecular formula. (ii) Write chemical equation to show its reaction with (1) Sodium metal (2) Excess conc. sulphuric acid (3) Ethanoic acid in the presence of an acid catalyst (4) Acidified potassium dichromate Also write the name of the product formed in each case.

Carbon is a versatile element that forms the basis of all living organisms and many of the things we use. A large variety of compounds is formed because of its tetrivalence. Compounds of carbon are formed with oxygen, hydrogen, nitrogen, sulphur, chlorine and many other elements. Answer the following questions: (a) What are hydrocarbons? (b) List two properties by virtue of which carbon can form a large number of compounds. (c) (i) Write the formula of the functional group present in (1) aldehydes, and (2) ketones. Write chemical equation for the reaction that occurs between ethanoic acid and ethanol in the presence of a catalyst. OR (c) (ii) What are structural isomers? Write the structures of two isomers of butane $(\mathrm{C}_4\mathrm{H}_{10})$.

More than three million carbon compounds have been discovered in the field of chemistry. The diversity of these compounds is due to the capacity of carbon atoms for bonding with one another as well as with other atoms. Most of the carbon compounds are poor conductors of electricity and have low melting and boiling points. (a) Write the molecular formula of first two members of homologous series having functional group -Br. (b) Given below are the formulae of some functional groups: $-CHO$, $-CO-$. Write the name of these functional groups. (c) What would be observed on adding a $5\%$ alkaline potassium permanganate drop by drop to some warm ethanol taken in a test tube? State the role of $KMnO_4$ in the reaction and write the chemical equation for the reaction involved. OR (c) Write the name of the compound formed when ethanol is heated at 443 K temperature with excess of conc. $H_2SO_4$. What is the role of conc. $H_2SO_4$ in the reaction? Write the chemical equation for the reaction involved.

The total number of electrons shared in the formation of an ethyne molecule is :

The correct representation of covalent bonding in an oxygen molecule is :

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

The electron dot structure of chlorine molecule is :

Assertion (A) : Melting point and boiling point of ethanol are lower than that of sodium chloride. Reason (R) : The forces of attraction between the molecules of ionic compounds are very strong.

(a) An acid 'X' and an alcohol 'Y' react with each other in the presence of an acid catalyst to form a sweet smelling substance 'Z'. Identify 'X', 'Y' and 'Z'. Write the chemical equation for the reaction involved and name it. The substance 'Z' on treatment with sodium hydroxide produces back the alcohol 'Y' and sodium ethanoate. Write the chemical equation for the reaction involved and name it, giving justification for the name. OR (b) (i) Name the simplest saturated hydrocarbon. Draw its electron dot structure. Which type of bonds exist in this compound? (ii) Name any two mixtures of the carbon compound used as a fuel in daily life, of which the above mentioned compound is an important component. (iii) In which homologous series of carbon compounds can this compound be placed? Write the general formula of the series. (iv) Which type of flame is produced on burning it?

(a) (i) A compound 'A' with a molecular formula of $C_2H_4O_2$ reacts with a base to give salt and water. Identify 'A', state its nature and the name of the functional group it possesses. Write chemical equation for the reaction involved. (ii) When the above stated compound 'A' reacts with another compound 'B' having molecular formula $C_2H_6O$ in the presence of an acid, a sweet smelling compound 'C' is formed. (1) Identify 'B' and 'C'. (2) State the role of acid in this reaction. (3) Write chemical equation for the reaction involved. OR (b) (i) Name the compound formed when ethanol is heated at $443 \text{ K}$ in the presence of conc. $H_2SO_4$ and draw its electron dot structure. State the role of conc. $H_2SO_4$ in this reaction. (ii) What is hydrogenation ? Explain it with the help of a chemical equation. State the role of this reaction in industry.

(a) A neutral organic compound $X'$ (Molecular formula $\mathrm{C_2H_6O}$) on reacting with acidified $\mathrm{K_2Cr_2O_7}$ gives an organic compound $Y'$ which is acidic in nature. $X'$ reacts with $Y'$ on warming in the presence of conc. $\mathrm{H_2SO_4}$ to give a sweet smelling compound $Z'$. (i) Identify $X'$, $Y'$ and $Z'$. (ii) Write the chemical equations for the reactions in the conversion of (1) $X'$ to $Y'$ and (2) $X'$ to $Z'$. (iii) State the role of (1) acidified $\mathrm{K_2Cr_2O_7}$ in the conversion of $X'$ to $Y'$ and (2) conc. $\mathrm{H_2SO_4}$ in the reaction of $X'$ and $Y'$. (iv) Name the reaction which occurs when $Z'$ reacts with an alkali. OR (b) Carry out the following conversions, stating the condition(s) for each : (i) Ethanol Ethene (ii) Ethene Ethane (iii) Ethane Chloroethane (iv) Ethanol Ethanoic acid (v) Ethanoic acid Ethyl ethanoate

(A) (i) Draw the structure of the following compounds : (a) Butanoic acid (b) Chloropentane (ii) How are structure (i) and structure (ii) given below related to one another ? Give reason to justify your answer. Draw one more possible structure for above case. (iii) Differentiate between saturated and unsaturated carbon compounds on the basis of their general formula. OR (B) (i) What happens when a small piece of sodium is dropped in ethanol ? Write the equation for this reaction. (ii) Why is glacial acetic acid called so ? (iii) What happens when ethanol is heated at $443 K$ in the presence of conc. $H_2SO_4$ ? Write the role of conc. $H_2SO_4$ in this case. (iv) Write an equation showing saponification.

(a) 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. OR (b) (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 $10\mathrm{mL}$ 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?

"Carbon prefers to share its valence electrons with other atoms of carbon or with atoms of other elements rather than gaining or losing the valence electrons in order to attain noble gas configuration." Give reasons to justify this statement.

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

Draw the electron dot structure of the following: (a) Cyclohexane (b) Butane

Consider the carbon compounds having following molecular formula: (i) $\mathrm{C}_3\mathrm{H}_6$ (ii) $\mathrm{C}_3\mathrm{H}_8$ (iii) $\mathrm{C}_4\mathrm{H}_6$ (iv) $\mathrm{C}_6\mathrm{H}_6$ (v) $\mathrm{C}_6\mathrm{H}_{12}$ (a) State the number of double covalent bonds present in $\mathrm{C}_3\mathrm{H}_6$ (b) Write the formula of first member of the homologous series to which the carbon compound $\mathrm{C}_4\mathrm{H}_6$ belongs. (c) Which one of the above compounds forms ring structure of carbon atoms? (d) Identify, which of the above compounds, is a member of alkane series.

Consider the following organic compounds : (i) $H-C(H)(H)-C(H)(H)-C(H)=O$ (ii) $H-C(H)(H)-C(H)=O (a) Name the functional group present in their compounds. (b) Write the general formula for the compounds of this functional group. (c) State the relationship between these compounds and draw the structure of any other compound having similar functional group.

(b) What is a homologous series? Find the difference in molecular mass between the two consecutive members of a homologous series. State how in a homologous series of carbon compounds the following properties vary with increase in molecular mass: (i) Melting and boiling points (ii) Chemical properties

(a) State the reason why: (i) carbon compounds have low melting and boiling points. (ii) carbon compounds do not conduct electricity. (iii) carbon can form only covalent compounds.

OR (a) Draw the electron dot structure for ethyne. (b) List two differences between the properties exhibited by covalent compounds and ionic compounds.

(a) 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. OR (b) (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?

"Two different forms of carbon – diamond and graphite have different structures and very different physical properties even though their chemical properties are same." Explain why. OR State the reasons, why carbon cannot (i) Lose four electrons to form $\mathrm{C}^{4+}$ cation, and (ii) Gain four electrons to form $\mathrm{C}^{4-}$ anion. How does carbon overcome this problem to form compounds?

Name a cyclic unsaturated carbon compound.

Covalent compounds are generally poor conductors of electricity. Why?

How are covalent bonds formed?

Covalent compounds have low melting and boiling point. Why?

Incomplete combustion of coal and petroleum: (A) increases air pollution. (B) increases efficiency of machines. (C) reduces global warming. (D) produce poisonous gases. The correct option is:

Assertion (A): Carbon has a strong tendency to either lose or gain electrons to attain noble gas configuration. Reason (R): Carbon has four electrons in its outermost shell and has the tendency to share electrons with carbon or other elements.

Assertion (A): Esterification is a process in which a sweet smelling substance is produced. Reason (R): When esters react with sodium hydroxide an alcohol and sodium salt of carboxylic acid are obtained. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

Assertion (A) : Ethanoic acid is also known as glacial acetic acid. Reason (R) : The melting point of pure ethanoic acid is 290 K and hence it often freezes during winters in cold climates.

Assertion (A): Following are the members of a homologous series: $\text{CH}_3\text{OH}, \text{CH}_3\text{CH}_2\text{OH}, \text{CH}_3\text{CH}_2\text{CH}_2\text{OH}$ Reason (R): A series of compounds with same functional group but differing by $-\text{CH}_2-$ unit is called a homologous series.

$3\text{ mL}$ of ethanol is taken in a test tube and warmed gently in a water bath. A $5\%$ solution of alkaline potassium permanganate is added first drop by drop to this solution, then in excess. (i) How is $5\%$ solution of $\mathrm{KMnO_4}$ prepared? (ii) State the role of alkaline potassium permanganate in this reaction. What happens on adding it in excess? (iii) Write chemical equation of this reaction.

Carbon, a member of group 14, forms a large number of carbon compounds estimated to be about three million. Why is this property not exhibited by other elements of this group? Explain.

(a) What is a homologous series? Explain with an example. (b) Define the following terms giving one example of each. (i) Esterification (ii) Addition reaction

(a) Compare soaps and detergents on the basis of their composition and cleansing action in hard water. (b) What happens when ethanol is treated with sodium metal? State the behaviour of ethanol in this reaction. (c) Draw the structure of cyclohexane. (d) Name the following compound: $$\text{CH}_3-\text{CH}_2-\text{OH}$$

(a) Define isomerism. Draw all possible isomers of butane. (b) "A compound 'X' on combustion gives a yellow flame with lots of smoke." What inference would you draw from this statement? (c) State the role of alkaline $KMnO_4$ in the reaction involving conversion of an alcohol to corresponding carboxylic acid.

Based on the group valency of elements write the molecular formula of the following compounds giving justification for each: (i) Oxide of first group elements. (ii) Halide of the elements of group thirteen, and (iii) Compound formed when an element, A of group 2 combines with an element B of group seventeen.

In three test tubes A, B and C, three different liquids namely, distilled water, underground water and distilled water in which a pinch of calcium sulphate is dissolved, respectively are taken. Equal amount of soap solution is added to each test tube and the contents are shaken. In which test tube will the length of the foam (lather) be longest? Justify your answer.

A compound ‘X’ on heating with excess conc. sulphuric acid at 443 K gives an unsaturated compound ‘Y’. ‘X’ also reacts with sodium metal to evolve a colourless gas ‘Z’. Identify ‘X’, ‘Y’ and ‘Z’. Write the equation of the chemical reaction of formation of ‘Y’ and also write the role of sulphuric acid in the reaction.

(a) Why are most carbon compounds poor conductors of electricity? (b) Write the name and structure of a saturated compound in which the carbon atoms are arranged in a ring. Give the number of single bonds present in this compound.

Write the molecular formula of the 2nd and 3rd member of the homologous series where the first member is ethyne.

Distinguish between esterification and saponification reactions with the help of the chemical equations for each. State one use of each (i) esters, and (ii) saponification process.

Write the structural formula of ethanol. What happens when it is heated with excess of conc. H₂SO₄ at 443 K? Write the chemical equation for the reaction stating the role of conc. H₂SO₄ in this reaction.

What happens when (write chemical equation in each case) (a) ethanol is burnt in air ? (b) ethanol is heated with excess conc. $H_2SO_4$ at 443 K ? (c) a piece of sodium is dropped into ethanol ?

Explain esterification reaction with the help of a chemical equation. Describe an activity to show esterification.

Why are certain compounds called hydrocarbons? Write the general formula for homologous series of alkanes, alkenes and alkynes and also draw the structure of the first member of each series. Write the name of the reaction that converts alkenes into alkanes and also write a chemical equation to show the necessary conditions for the reaction to occur.

Mention the essential material (chemicals) to prepare soap in the laboratory. Describe in brief the test of determining the nature (acidic/alkaline) of the reaction mixture of saponification reaction.

Write the name and structure of an aldehyde with four carbon atoms in its molecule.

Write the name and structure of an alcohol with four carbon atoms in its molecule.

Write chemical equation of the reaction of ethanoic acid with the following: (a) Sodium; (b) Sodium hydroxide; (c) Ethanol. Write the name of one main product of each reaction.

An aldehyde as well as a ketone can be represented by the same molecular formula, say $C_3H_6O$. Write their structures and name them. State the relation between the two in the language of science.

On dropping a small piece of sodium in a test tube containing carbon compound ‘X’ with molecular formula $C_2H_6O$, a brisk effervescence is observed and a gas ‘Y’ is produced. On bringing a burning splinter at the mouth of the test tube the gas evolved burns with a pop sound. Identify ‘X’ and ‘Y’. Also write the chemical equation for the reaction. Write the name and structure of the product formed, when you heat ‘X’ with excess conc. sulphuric acid.

Write three different chemical reactions showing the conversion of ethanoic acid to sodium ethanoate. Write balanced chemical equation in each case. Write the name of the reactants and the products other than ethanoic acid and sodium ethanoate in each case.

A carbon compound ‘P’ on heating with excess conc. $H_2SO_4$ forms another carbon compound ‘Q’ which on addition of hydrogen in the presence of nickel catalyst forms a saturated carbon compound ‘R’. One molecule of ‘R’ on combustion forms two molecules of carbon dioxide and three molecules of water. Identify P, Q and R and write chemical equations for the reactions involved.

A student puts a drop of reaction mixture of a saponification reaction first on a blue litmus paper and then on a red litmus paper. He may observe that:

For preparing soap in the laboratory we require an oil and a base. Which of the following combinations of an oil and a base would be best suited for the preparation of soap?

In the neighbourhood of your school, hard water required for an experiment is not available. Select from the following groups of salts available in your school, a group each member of which, if dissolved in distilled water, will make it hard:

A student puts a drop of reaction mixture of a saponification reaction first an a blue litmus paper and then on a red litmus paper. He may observe that :

A student adds a spoon full of powdered sodium hydrogen carbonate to a flask containing ethanoic acid. List two main observations, he must note in his note book, about the reaction that takes place. Also write chemical equation for the reaction.

Write the name and formula of the 2nd member of homologous series having general formula $C_nH_{2n}$.

With the help of an example, explain the process of hydrogenation. Mention the essential conditions for the reaction and state the change in physical property with the formation of the product.

What is the difference between the molecules of soaps and detergents, chemically? Explain the cleansing action of soaps.

Explain why carbon forms compounds mainly by covalent bond. Explain in brief two main reasons for carbon forming a large number of compounds. Why does carbon form strong bonds with most other elements?

A student adds 2 mL of acetic acid to a test tube containing 2 mL of distilled water. He then shakes the test tube well and leaves it to settle for some time. After about 5 minutes he observes that in the test tube there is:

A student prepared 20% sodium hydroxide solution in a beaker to study saponification reaction. Some observations related to this are given below: (I) Sodium hydroxide solution turns red litmus blue (II) Sodium hydroxide readily dissolves in water (III) The beaker containing solution appears cold when touched from outside (IV) The blue litmus paper turns red when dipped into the solution. The correct observations are:

Hard water is not available for an experiment. Some salts are given below: (I) Sodium chloride (II) Sodium sulphate (III) Calcium chloride (IV) Calcium sulphate (V) Potassium chloride (VI) Magnesium sulphate. Select from the following a group of these salts, each member of which may be dissolved in water to make it hard.

List two observations which you make when you add a pinch of sodium hydrogen carbonate to acetic acid in a test tube. Write chemical equation for the reaction that occurs.

Write the name and the structural formula of the compound formed when ethanol is heated at 443 K with excess of conc. $H_2SO_4$. State the role of conc. $H_2SO_4$ in this reaction. Write chemical equation for the reaction.

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.

(a) Define the term ‘isomers’. (b) Draw two possible isomers of the compound with molecular formula $C_3H_6O$ and write their names. (c) Give the electron dot structures of the above two compounds.

Hard water required for an experiment is not available in a school laboratory. However, following salts are available in the laboratory. Select the salts which may be dissolved in water to make it hard for the experiment. (1) Calcium Sulphate (2) Sodium Sulphate (3) Calcium Chloride (4) Potassium Sulphate (5) Sodium Hydrogen Carbonate (6) Magnesium Chloride

Name the functional group present in each of the following organic compounds : (i) $C_2H_5Cl$ (ii) $C_2H_5OH$

Write the name and formula of the second member of the carbon compounds having functional group - OH.

Write the name and formula of the first member of the series of carbon compounds having functional group - C - OH.

List the products of combustion of fossil fuels. What are their adverse effects on the environment ?

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?

What is meant by homologous series of organic compounds ? Write the chemical formulae of two members of a homologous series and state which part determines the (i) physical properties, (ii) chemical properties, of these compounds.

What are isomers? Draw the structures of two isomers of butane, $C_4H_{10}$. Why can’t we have isomers of first three members of alkane series?

(a) With the help of a suitable example, explain the process of hydrogenation mentioning the conditions of the reaction and any one change in physical property with the formation of the product. (b) How does a saturated hydrocarbon react with chlorine? Write chemical equation for it. What type of reaction is it called and why? OR What are soaps and detergents chemically? Explain the action of cleaning by soaps. State the reason why we can wash our clothes even in hard water using detergents.

What is the difference between the chemical composition of soaps and detergents? State in brief the action of soaps in removing an oily spot from a shirt. Why are soaps not considered suitable for washing where water is hard ? Or List in tabular form three physical and two chemical properties on the basis of which ethanol and ethanoic acid can be differentiated.

What are hydrocarbons ? Write the name and general formula of (i) saturated hydrocarbons, (ii) unsaturated hydrocarbons, and draw the structure of one hydrocarbon of each type. How can an unsaturated hydrocarbon be made saturated ? OR What are detergents chemically ? List two merits and two demerits of using detergents for cleansing. State the reason for the suitability of detergents for washing, even in the case of water having calcium and magnesium ions.

On adding 2 mL acetic acid to 2 mL of water in a test tube, it was observed that

Which of the following observations is true about dilute solution of acetic acid?

On adding acetic acid to sodium hydrogen carbonate in a test tube, a student observes

In a litmus test it is observed that an aqueous solution of acetic acid turns

A student takes $Na_2CO_3$ powder in a test tube and pours some drops of acetic acid over it. He observes :

Which one of the following are the correct observations about acetic acid ?

A student adds 4 mL of acetic acid to a test tube containing 4 mL of distilled water. He then shakes the test tube and leaves it to settle. After about 10 minutes he observes :

A student takes four test tubes marked a, b, c and d containing NaCl, Na₂CO₃, NaHCO₃ and NaOH respectively. He adds acetic acid to the test tubes one by one and every time he immediately brings a lighted match-stick near to the mouth of the test tube. He observes that the match-stick extinguishes in the cases of

How many covalent bonds are there in a molecule of ethane, $\text{C}_2\text{H}_6$?

Butanone is a four-carbon per molecule compound. Name the functional group present in it.

(a) What is a homologous series of compounds ? List any two of its characteristics. (b) What is the next higher homologue of $C_3H_7OH$ ? What is its formula and what is it called ?

Write one chemical equation to represent each of the following types of reactions of organic substances: (i) Esterification (ii) Saponification (iii) Substitution

(a) In a tabular form, differentiate between ethanol and ethanoic acid under the following heads: (i) Physical state (ii) Taste (iii) $\text{NaHCO}_3$ test (iv) Ester test (b) Write a chemical reaction to show the dehydration of ethanol. OR (a) What is a soap? Why are soaps not suitable for washing clothes when the water is hard? (b) Explain the action of soap in removing an oily spot from a piece of cloth.

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 burns with a sooty flame. (v) Kerosene does not decolourise Bromine water while cooking oils do. OR (a) What is a detergent ? Name one detergent. (b) Write two advantages and two disadvantages of using detergents over soaps. (c) Why, by using a detergent, can we wash clothes even in hard water ?

On shaking acetic acid with water

Acetic acid smells like:

When solid sodium bicarbonate is added to a dilute aqueous solution of ethanoic acid

Acetic acid solution turns:

On adding $\text{NaHCO}_3$ to acetic acid, a gas is evolved which turns lime water milky due to the formation of:

As observed in the school laboratory, acetic acid is

A student added acetic acid to test tubes I, II, III and IV containing the labelled substances (I: $NaOH$, II: $NaCl$, III: $NaHCO_3$, IV: $Ca(OH)_2$) and then brought a burning splinter near the mouth of each test tube. The splinter would be extinguished when brought near the mouth of test tube

State two characteristic features of carbon which when put together give rise to a large number of carbon compounds.

Name the functional group of organic compounds that can be hydrogenated. With the help of suitable example explain the process of hydrogenation mentioning the conditions of the reaction and any one change in physical property with the formation of the product. Name any one natural source of organic compounds that are hydrogenated.