CBSE Class 10 Science Carbon and its compounds Assignment Set B

Question. The soap molecule has a -
a) hydrophilic head and hydrophilic tail
b) hydrophobic head and hydrophilic head
c) hydrophobic head and hydrophobic tail
d) hydrophilic head and hydrophobic tail
Answer : D

Question. Identify the unsaturated compounds from the following
(i) Propane (ii) Propene (iii) Propyne (iv) Chloropropane
(a) (i) and (ii)
(b) (ii) and (iv)
(c) (iii) and (iv)
(d) (ii) and (iii)
Answer : D

Question. The functional group present in propanal is
a) -OH
b) -COOH
c) -CO-
d) -CHO
Answer : D

Question. Buckminsterfullerene is an allotropic form of
(a) phosphorus
(b) sulphur
(c) carbon
(d) tin
Answer : C

Question. Which of the following statements are usually correct for carbon compounds? These
(i) are good conductors of electricity
(ii) are poor conductors of electricity
(iii) have strong forces of attraction between their molecules
(iv) do not have strong forces of attraction between their molecules
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)
Answer : D

Question. When vegetable oil is treated with hydrogen in the presence of nickel
Or (Palladium) as a catalyst, it forms vegetable ghee. This process shows
a) Anodising reaction
b) Substitution reaction
c) Displacement reaction
d) Addition reaction
Answer : D

 

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. 

Question : The structural formula of ethyl ethanoate

Answer : B

Question : The compound which gives a brisk effervescence with sodium metal and not with sodium hydrogen carbonate is
(a) ethanol
(b) ethanoic acid
(c) both ethanoic acid and ethanol
(d) none of these
Answer : A

Question : Which is denatured spirit?
(a) ethanol only
(b) ethanol and methanol (50%)
(c) ethanol and methanol (5%)
(d) methanol only
Answer : C

Question : Drinking alcohol and driving may cause serious accidents. To discourage this, police randomly test drivers for alcohol using a breath analyser. The breath analyser works because
(a) Alcohol makes the breath dry and the machine registers moisture
(b) Alcohol makes the breath hotter which changes the machine reading
(c) Alcohol causes more saliva which the machine checks.
(d) Alcohol in the breath cause a chemical change registered by the machine.
Answer : B

Question : The by product of soap is
(a) isoprene
(b) glycerol
(c) butene
(d) ethylene glycol
Answer : B

Question : Tertiary butane gets oxidised with oxidising agents like alkaline KMNO4 to
(a) Isobutane
(b) Ter-butyl alcohol
(c) Secondary-propyl alcohol
(d) All of above
Answer : B

Question : According to IUPAC system, the correct name of the organic compound is

(a) 2-bromobutanoic acid
(b) 2-bromobutysis acid
(c) 3-bromobutanoic acid
(d) 3-bromo-2-hydroxybutan-2-one
Answer : C

Question : The substance not responsible for the hardness of water is
(a) sodium nitrate
(b) calcium hydrogen carbonate
(c) calcium carbonate
(d) magnesium carbonate
Answer : A

Question : The isomeric pair is
(a) ethane and propane
(b) propane and butane
(c) ethane and ethane
(d) butane and 2-methyl propane
Answer : D

Question : Soaps are formed by saponification of
(a) alcohols
(b) glycosides
(c) simple esters
(d) carboxylic acids
Answer : D

Question : Identify the product formed when methane reacts with chlorine in the presence of sunlight is
(a) C₂Cl₆
(b) CH₃Cl
(c) CHCl₄
(d) None of these
Answer : B

Question : Covalent compounds
(a) have high melting and boiling points
(b) are mostly soluble in water
(c) are formed between atoms of metals and non-metals
(d) are formed by the sharing of electrons in the bonding atoms.
Answer : D

Question : Vinegar is a solution of
(a) 30% – 40% acetic acid in alcohol
(b) 5% – 8% acetic acid in alcohol
(c) 5% – 8% acetic acid in water
(d) 15% – 20% acetic acid in water
Answer : C

Question : Which of the following can be used for the denaturation of ethyl alcohol?
(a) Methyl alcohol
(b) Pyridines
(c) Copper sulphate
(d) All of above
Answer : D

Question : The correct electron dot structure of a water molecule is

Answer : C

Question : Acetic acid was added to a liquid X kept in a test tube. A colourless and odourless gas Y was evolved. The gas was passed through lime water which turned milky. It was concluded that:
(a) Liquid X is sodium hydroxide and the gas Y is CO₂
(b) Liquid X is sodium carbonate and the gas Y is CO₂
(c) Liquid X is sodium acetates and the gas Y is CO₂
(d) Liquid X is sodium chloride and the gas Y is SO₂.
Answer : B

 

Very Short Answers

Question : Draw electron dot structure of carbon dioxide and write the nature of bonding between carbon and oxygen in its molecule. 
Answer :
 ..         ..
:O: :C: :O    : or O = C = C
 ..        ..
Covalent bond (double bond) is present in between C and O.

Question : List two properties of carbon which lead to the huge number of carbon compounds we see around us, giving reason for each. 
Answer : Two properties of carbon which lead to the huge number of carbon compounds are :
(a) Catenation : It is the ability of carbon to form bonds with other atoms of carbon.
(b) Tetravalency : With the valency of four, carbon is capable of bonding with 4 other atoms.
This forms huge number of compounds.

Question : List two chemical properties on the basis of which ethanol and ethanoic acid may be differentiated and explain how. Unsaturated hydrocarbons contain multiple bonds between two carbon atoms and these compounds show addition reactions. Out of saturated and unsaturated carbon compounds, which compounds are more reactive ? Write a test to distinguish ethane from ethene.
Answer :
(a) Ethanol does not react with sodium bicarbonate but ethanoic acid reacts with sodium bicarbonate releasing CO₂ gas.
(b) Ethanol does not change the colour of blue litmus paper but ethanoic acid changes the colour of blue litmus to red due to presence of carboxylic acid group. Unsaturated carbon compounds are more reactive than saturated carbon compounds. Bromine water is decolourized by ethene but there is not change of colour of bromine water with ethane.

Question : Carbon has four electrons in its valence shell. Which type of compounds can be formed by carbon atom and why ? Give any one example of such compounds.
Answer : Covalent compounds can be formed by carbon atom because carbon atom has 4 valence electrons, hence it is not able to gain four electrons or form C^4– ion or lose four electrons or form C⁴⁺ ion to attain noble gas configuration. So, it shares electrons to form covalent bonds and the covalent compounds.
Example : CH₄ (methane) compounds.

Question : In a school laboratory the students are studying the properties of ethanoic acid through certain experiments. How can they test its acidic nature ? Give two tests.
Answer :
(a) Blue litmus turns red.
(b) On adding solid sodium carbonate or sodium hydrogen carbonate, brisk effervescence is observed.

Question : If you add a few drops of acetic acid to a test tube containing (i) distillated water and (ii) aqueous solution of sodium hydrogen carbonate, what would you observe ? If a reaction takes place in any one of the above two cases, list its two observations.
Answer :
(a) No reaction with distilled water.
(b) Chemical reaction occurs with solution of NaHCO₃.
Two observations are :
(i) Evolution of a colourless, odourless gas.
(ii) The gas is evolved with brisk effervescence.

Question : Write the molecular formula of (a) Methane and (b) Ethanol.
Answer :
(a) CH₄ (b) C₂H₅OH or C₂H₆O

Question : You have four beakers A, B, C and D. Out of A and B one has hard water and the other has soft water. Out of C and D one has soap solution and the other has detergent-solution. How would you identify these liquids ? 
Answer : On adding soap solution lather will be formed in the beaker containing soft water only. While On adding detergent solution lather will be formed by both hard and soft water in both the beakers.

Question : What do you observe when you add sodium bicarbonate to acetic acid ? How would you identify the gas released in the reaction ? Describe briefly.
Answer : A colourless gas with brisk effervescence will be evolved which turns the lime water milky. When this gas is passed through it.

Question : Write the molecular formula of (a) ethane and (b) ethanoic acid 
Answer :
(a) C₂H₆
(b) CH₃COOH

Question : Write the name of (a) CH₄ and (b) CH₃COOH.
Answer :
(a) Methane
(b) Ethanoic acid or Acetic acid

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.

 

Question : 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.
Answer : The essential chemicals required to prepare soap in the laboratory are oil and sodium hydroxide solution. In order to determine the nature of the reaction mixture of saponification reaction, we dip red litmus paper into it which will turn blue after a while indicating that it is a basic mixture.

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.