CBSE Class 10 Science Carbon and its compounds Assignment Set B

 

Question : Diamond is not a good conductor of electricity because: 

a. It is not soluble in water.

b. It is very hard.

c. It has no free electrons to conduct electric current.

d. Its structure is very compact.

Answer : C 

Explanation: Diamond is not a good conductor of electricity because it has no free electrons in its structure (like graphite) to conduct electric current. 

 

Question : Substance ‘X’ is formed by the reaction of carboxylic acid and alcohol. It is used in making ice creams, cold drinks, perfumes and in flavoring agent. Name ‘X’. 

a. Aldehyde

b. Alkyne

c. Ester

d. Ketone

Answer : C 

Explanation: Substance X is an ester. The reaction in which a carboxylic acid combines with an alcohol to form an ester is called esterification. Some volatile esters with characteristic odours are used in synthetic flavours, perfumes, and cosmetics. Certain volatile esters are used as solvents for lacquers, paints, and varnishes; large quantities of ethyl acetate and butyl acetate are commercially produced for this purpose.

 

 

Question : Which one of the following is not in liquid state at 10°C? 

a.  H₂O

b. Glacial acetic acid

c.  C₂H₅OH

d. Acetone

Answer : B

Explanation: Freezing point of pure ethanoic acid is 16.6 °C (61.9 °F). Freezing point of pure water is 0 °C. Freezing point of pure ethyl alcohol (C₂H₅OH) is -114.1 °C. Freezing point of pure acetone is -95 °C. When ethanoic acid (acetic acid) is cooled below 10 °C, it freezes to form a colourless, ice-like solid. The solid looks like glacier and hence pure ethanoic acid is called glacial ethanoic acid (or glacial acetic acid).

 

Question : Statement A: Ethane decolorizes bromine water whereas ethyne does not.

Statement B: Mixture of water and alcohol is used in radiators of vehicles in cold countries. 

a. Statement B is true; Statement A is false.

b. Both - Statement A and Statement B - are true.

c. Statement A is true; Statement B is false.

d. Both - Statement A and Statement B - are false.

Answer : A

Explanation: Bromine water test is a test for unsaturated hydrocarbons.

Ethane undergoes addition reaction and decolorizes bromine water. Similarly, ethyne also decolorizes bromine water. Mixture of water and alcohol is used in radiators of vehicles in cold countries.

Alcohol is used for antifreeze mixture. Antifreeze is an additive which lowers the freezing point of a water-based liquid.

 

Question : Which among the following is a cleaner fuel? 

a. C₆H₁₂O₆

b. CH₃OH

c. C₃H₇OH

d. C₂H₅OH

Answer : D

Explanation: Ethanol (C₂H₅OH ) is a cleaner fuel. It is used as a fuel in cars along with petrol. It is also used as a fuel in spirit lamps. 

 

Very Short Answers

 

Question : Would you be able to check if water is hard using a detergent? 

Answer :  No, we can't check whether the water is hard or soft using a detergent. 

 

Question :  Which ions are responsible for making water hard? 

Answer :   Calcium ions (Ca²⁺) and magnesium ions (Mg²⁺) are responsible for making the water hard. 

 

Question : What are constituents of an antifreeze? 

Answer :  Ethylene glycol or ethanol is used as an antifreeze.

 

Question : Complete the following reaction, 

CH₂ = CH₂ + Cl₂ →

Answer : 

Short Answers

 

Question : Write the name and chemical formula of the simplest organic acid. 

Answer :  Formic acid is the simplest organic acid.

 

Question : Diamond is a poor conductor of electricity while graphite is a good conductor. Give reason. 

Answer :  In diamond, all the four valence electrons of carbon are involved in the formation of covalent bonds. Thus, no free electrons are available to conduct electricity. Whereas, in graphite, three electrons in the valence shell of carbon are involved in the formation of covalent bond. The fourth electron is free to move. So,it conducts electricity.

 

Question : Give names of the following: 

(a) An aldehyde derived from ethane

(b) Ketone derived from butane

(c) Compound obtained by the oxidation of ethanol by chromic anhydride

Answer :

Question : Name the product formed when an organic acid and alcohol react in the presence of acid catalyst. Write the equation and give two uses of the product formed.  

Answer :  When an organic acid and alcohol reacts ester is formed by the process is known as esterification reaction for e.g. formation of ethyl ethanoate which is a ester of ethanoic acid and ethanol. Reaction is given as:

 

Ester is used in preparing perfumes and flavouring agents.

 

 

Long Answers

 

Question : An organic compound A is widely used as a preservative in pickles and has a molecular formula C₂H₄O₂. This compound reacts with ethanol to form a sweet smelling compound B.

i. Identify the compound A.

ii. Write the chemical equation for its reaction with ethanol to form compound B.

iii. How can we get compound A form B?

iv. Name the process and write corresponding chemical equuation.

v. Which gas is produced when compound A reacts with washing soda? Write the chemical equation. 

Answer :

i. A is ethanoic acid (CH₃COOH). Commonly, known as acetic acid. Its 5 % solution in water is used to prepare vinegar, which is used as preservatives for pickles.

 

Question : Identify the compounds A to E in the following reaction sequence. 

 

Answer :

 

Question : Name the compound form heating ethanol at 443 K with excess of conc.H₂SO₄. 

Question : What happened when a small piece of sodium is dropped into ethanol ? 

Question : Write the chemical equation for the decarboxylation of ethanoic acid? 

Question : Give an example of esterification reaction. 

Question : Name the product obtained when ethanol is oxidized by either chromic anhydride or alkaline potassium permanganate. 

Question : Write the chemical equation repressing the preparation reaction of ethanol from ethane. 

Question : Name the 2 elements which are present both in CNG and Petroleum 

Question : Draw the electronic dot structure of ethane molecule (C₂H₆) 

Question : Write the IUPAC name of the next homologous of CH₃OHCH₂CH₃. 

Question : Define homologous series of organic compounds series of organic compounds ,Mention any two characteristics of homologous series. 

Question : Describe a chemical test to distinguish between ethanol and ethanoic acid. 

Question : Give the name of functional groups (i)-CHO (ii) –C=0 

Question : Why does carbon form compounds mainly by covalent bonding ? 

Question : Give a chemical test to distinguish ethanol from ethanoic acid. 

Question : Allotropy is a property shown by which class: substances elements compounds or mixtures ? give one examples of allotropy. 

Question : How may be the following be obtained from ethanol ? express giving chemical equations. (i) Ethyl ethanoate (ii) Sodium ethoxide. 

Question : Describe with chemical equation how ethanoic acid may be obtained from. (i) Ethanol (ii) Methanol 

Question : Explain the cleansing action of soap 

Question : Distinguish between esterification and saponification reactions of organic compounds 3.

Question : Explain the structure of graphite in term of bonding and give one property based on this structure. 

Question : Name the organic acid present in vinegar .write a chemical equation which represents the commercial method for the preparation of this acid from methanol.

(HOTS) QUESTIONS:

Question : Why the colour of potassium permangante disappers,if it is added to warm solution of ethanol.

Question : An organic compound with molecular formula C₂H₄O₂ produces brisk effervescence on addition of sodium carbonate /bicarbonate.

a .Identify the organic compound.

b. Name the gas evolved.

C. How will you test the gas evolved.

d. Write the chemical equation for the above reaction.

e. List two important uses of the above compound.

Question : a.What are the various possible structure formulae of a compound having molecular formula C₃H₆O .

b. Also give the IUPAC names of the above possible compounds.

c.What is the similarity in these compounds?

Question : A mixture of oxygen and ethyne is burnt for welding ,can you tell why a mixture of ethyne and air is not used .

Question : Two carbon compound A and B have molecular formula C₃H₈ and C₃H₆ respectively. Which one of the two is most likely to show addition .justify your answer .Explain with the help of a chemical equation ,how an addition reaction is used in vegetable ghee industry. 

Question : 1ml glacial acetic acid and 1ml of ethanol are mixed together in a test tube. Few drops of concentrated sulphuric acid is added in the mixture are warmed in a water bath for 5 min.

a. Name the resultant compound formed.

b. Represent the above change by a chemical equation .

c.What term is given to such a reaction.

d. What are the special characteristics of the compound formed.

Question : An organic compound 'X‘with a molecular formula C₂H₆O undergoes oxidation in the presence of alkaline KMnO4 and forms the compound 'Y‘. 

a. Identify 'X‘ and 'Y‘

b.Write your observation when the compound 'X‘ is made to react with compound 'Y‘ which is used as a preservative for pickles.

PUZZLE :

1. Compounds containing double and triple bonds.

2. A compound which is basic constituent of many cough syrups.

3. Very dilute solution of ethanoic acid.

4. A sweet smelling substance formed by the reaction of alcohol and carboxylic acids.

5. Gas released when sodium metal is dropped in ethanol.

6. The functional group present in methanol.

7. IUPAC name of alkene containing 3 carbon atoms.

8. The number of single covalent compounds present in pentane.

9. First member of homologous serious alkyne.

10. Simplest ketone.

11. Self linking property of carbon.

12. Product formed by dehydration of ethanol in conc. Sulphuric acid.

13. Alcohol whose intake in small quantities can be lethal.

14. Number of single covalent bounds in ammonia.