CARBON AND ITS COMPOUNDS – 2020 Important Question

1 MARK QUESTIONS

Q1. “Carbon tetrachloride is not a good conductor of electricity”. Justify?

Q2. Why is fullerene so called?

Q3. What is the composition of natural gas used for cooking?

Q4.  What do you mean by the term soapless soaps?

Q5. What is the disadvantage of detergents over soaps?

Q6. Molecular formula of a hydrocarbon is C3H8   Write is name and draw its complete structure.

Q7. Write the name and structure of an alcohol with three carbon atoms in its molecule.

Q8. Name the functional group present in CH3COCH3 and state the name of this compound.

Q9. Why are mineral acids stronger acids than carboxylic acids?

Q10. Why do alkanes burn with blue or clean flame?

Q11.   How two successive members of a homologous series differ from each other?

Q12.   Graphite is a covalent molecule but a good conductor of electricity. Why?

Directions (Q. Nos.  13- 17)  In the following questions a statement of Assertion is

followed by a statement of Reason. Mark the correct choice as:          

(a) If both  Assertion and Reason are true and Reason is the correct explanation of Assertion.

(b)  If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

(c)  If Assertion is true but Reason is false.

(d)  If Reason is true but Assertion is false.

(e) If both  Assertion and Reason are false.

Q13. Assertion: Branched-chain alkanes have lower boiling points.

            Reason: As molecular size decreases, boiling point increases.

Q14. Assertion: Olefins have the general formula  CnH2n

            Reason: There is one triple bond between two carbon atoms in their molecules.

Q15.  Assertion: Denatured alcohol is Ethyl Alcohol when mixed with Methanol

             Reason: Denaturing of alcohol prevents misuse of alcohol meant for Industrial use.

Q16.  Assertion: Acetic Acid is an inorganic solvent.

             Reason: Inorganic chemicals are soluble in Acetic Acid.

Q17.  Assertion: Cleaning action of soaps is due to formation of miscelles.

             Reason: Miscelles are formed when hydrophilic part of the soap molecule

Q14. When you add a few drops of  acetic acid to a test-tube containing sodium bicarbonate powder, which one of the following is your observation?

(a ) No reaction takes place.

(b) A  colourless gas with pungent smell is released with brisk effervescence.

(c) A  brown coloured gas is released with brisk effervescence.

Q15. Choose the correct general formula of alkane.

(a) CnH2n-2           

(b) C2nH2n+2

(c) CnH2n       

(d) CnH2n+2

Q16. According to given figure,  how many electrons are being shared by each oxygen.

(a) 2        

(b) 3                          

(c)  1                 

(d) 4

3 MARK QUESTIONS

Q1.   Compound  A has three carbon atoms,  which bums with non-sooty flame. Predict what is A? Write its electron dot structure.

Q2.    Give reasons for the following.

(i)  Ethanoic acid is used in the preservation of pickles.

(ii) CO2   is released on burning diamond as well as graphite.

Q3. An organic compound X of molecular formula C2H4O2 turns blue litmus to red and give brisk effervescence with Na2CO3 and NaHCO3. Identify X and name of the gas responsible for effervescence.

Q4.  Give answers to the following statements.

(i) An allotrope of carbon which has a two-dimensional layered structure consisting of fused benzene rings.

(ii)   An allotrope of carbon which looks like a soccer ball.

(iii)  An allotrope of carbon which contains both single and double bonds.      

Q5. Give the molecular formula and electron dot structure of ethyne and ethene.        

Q6. Define homologous series.  Examine it with an example.  Will there be any change in their physical properties? Give reason for your answer.                                        

Q7. What are soaps chemically? How do they differ from synthetic detergents? Also, mention their uses?

Q8. Give reason why carbon can neither form C4+ cations nor C4- anions , but forms covalent compounds. Also state the reason to explain why covalent compounds are bad conductors of electricity and have low melting and boiling points?

Q9. Draw the structures of the following compounds and   identify the   functional group present them:

(i) Butanoic acid

(ii) Bromopropane

(iii) Butyne

Q10. What is meant by homologous series of carbon compounds? Write the general formula of (i) alkenes, and  (ii)  alkynes. Draw the structures of the first member of each series to show the bonding between the two carbon atoms.

Q11. Write the name and general formula of a chain of hydrocarbons in which an addition reaction with hydrogen can take place. Stating the essential conditions required for an addition reaction to occur, write the chemical equation giving the name of the reactant and the product of such a reaction. 

Q12. Explain the following:

(i) CH3COOH is a weak acid.

(ii) Propene undergoes addition reaction.

(iii) The gas stoves have inlets for air.

Q13. Two carbon compounds X   and    Y   have the molecular formula C3H6 and C4H10 respectively. Which one of the two is most likely to show addition reaction? Justify your answer. Also give the chemical equation to explain the process of addition reaction in this case.

Q14. Explain why it is difficult to wash clothes with soap when water is hard. How do detergents help in overcoming this problem?

Q15. 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.

Q16. Write the name and molecular formula of  an organic compound having its name suffixed with ‘ol’ and having two carbon atoms  in its molecule. Write balanced chemical equation to indicate what happens when this compound is heated with excess  conc. H2SO4 and  the name  of  main product formed. Also state the role of conc.  H2SO4 in the reaction.

Q17. Complete the following chemical equations :

Carbon compounds_1

 
 Q18. An organic compound ‘P’ is a constituent of wine. ‘P’ on reacting with acidified K2Cr207 forms another compound ‘Q’. When a piece of sodium is added to ‘Q’ a gas ‘R’ evolves which burns with a pop sound. Identify P, Q and  R and write the chemical equations of the reactions involved.

Q19. What are esters? How they are prepared? List two uses of esters.

Q20. How are the following products obtained from ethanol?

(i) Ethyl ethanoate

(ii) Sodium ethoxide.

Q21. An organic compound ‘N  of molecular formula C2H60 on oxidation  with dilute alkaline KMnO4 solution gives an acid ‘B’  with the same number of carbon atoms. Compound ‘A’  is often used for sterilization of skin by doctors.

(i) Name the compounds ‘A’ and ‘B’.

(ii) Write the chemical equation involved in the formation of B from A.

Q22. The molecules of alkene family are represented by a general formula, CnH2n.  Now answer the following.

(a) Wl1at is the name of alkene when n = 47

(b) What is the molecular formula of alkene, when n = 67

(c) What is the molecular formula and structural formula of the first member of the alkene family?

Q23. (a) Which among the following C2H6 , C2H5OH, CH3COOH is a hydrocarbon?

            (b) Differentiate between saturated and unsaturated hydrocarbons.  Give one example for each.

Q24. What is the role of metal or reagents written on arrows in the given chemical reactions?

Carbon compounds_2

Q25.  (i) Why does carbon form largest number of compounds? Give two reasons.            

             (ii)  Why are some of these called saturated and the other unsaturated compounds?

            (iii)  Which one of these two is more reactive and why?

5 MARK QUESTIONS 

Q1. Define structural isomer and draw the isomeric structures of butane. Compare the structure of benzene and cyclohexane by drawing them.                           

Q2. What is the difference between combustion and oxidation? Under what condition an oxidation reaction can be called as combustion? Illustrate your   answer with one example in each case.

Q3.   (i)   State the litmus test to distinguish between an alcohol and a  carboxylic acid.

           (ii)   Give the equation for the reaction of a carboxylic acid with an alcohol.  State the condition for the reaction and name the product formed.  What is this reaction known as?

          (iii) Write a reaction which is reverse of this reaction? Mention the conditions required for the reaction.  Name and write the use of this reaction.

Q4. 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 from B?

(iv) Name the process and write corresponding chemical equation.

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

Q5. 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.

Q6. (a)Draw  the structure for the following compounds:

(i) 2-Bromopentane,

(ii) 2-methyl propane,

(iii) Butanal,

(iv) 1-Hexyne.

      (b) Draw the electron dot structure for ethanoic acid.

Q7. List two reasons for carbon forming a large number of compounds. Name the type of bonding found in most of its compounds. Why does carbon form compounds mainly by this kind of bonding. Give reason why the carbon compounds:

(i) Generally have low melting and boiling points.

(ii) Do not conduct electricity in molten state.

Q8. Soaps and detergents are both types of salts.  State the difference between the two.  Write the mechanism of the cleansing action of soaps.  Why do soaps not form lather  (foam) with hard water? Mention any two problems that arise due to the use of detergents instead of soaps.

Q9. What are micelles? Why does it form when soap is added to water? Will a micelle be formed in other solvents such as ethanol also? State briefly how the formation of micelles help to clean the clothes having oily spots. 

Q10. A compound A (C2H4O2)  reacts with Na metal to form a compound  ‘B’ and evolved a gas which burns with a  pop sound.   Compound   ‘X   on treatment with an alcohol ‘C’ in presence of an acid forms a Sweet smelling compound  ‘D’ (C4H8O2). On addition of NaOH to ‘D’ gives back Band C. Identify C and D write the reactions involved.

Q11. A carbon compound  ‘P’ on heating with excess conc. H2SO4  forms another carbon compound ‘Q’ which on the 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.

Q12. Make the structure of methane by showing sharing of electrons between carbon and hydrogen atoms. How could you convert methane into chloroform by substitution reaction? Explain with the help of chemical reactions.

Q13. (a) A compound  X  with molecular formula, C2H4   burns with a sooty flame. It decolourises bromine water. Identify X. Will it dissolve in water or not? Will it conduct electricity in aqueous solution?

            (b) An organic compound X is an essential constituent of-wine and beer, which is responsible for intoxication caused by these drinks. Oxidation of X  yields an organic acid Y, which is present in vinegar. Name the compounds X and Y.

Q14. (a) An element of group 14 has two common allotropes, A and 8. A is very hard and is bad conductor of electricity while 8 is soft to touch and good conductor of electricity. Identify the element and its allotropes.  Explain reasons for their different properties.

           (b) How can we distinguish ethanoic acid and ethanol using their chemical properties? Write any three differences.

Q15.       How are the following pairs related?

(i)  2, 2-dimethylpropane and 2-methylbutane

(ii)  Ethane and  propane

(iii) C2H5Cl and C3H7Cl

(iv)  C3H4 and C2H4

Q16 .      Draw  the structures  of

(i) Chlorohexane

(ii)  Butanol

(iii)  Propanone  

(iv)  Sodium  Ethanoate

(v) Butanoic Acid

(vi)  Butyraldehyde

(vii)  Sodium  Ethoxide 

(viii)  Sodium  Stearate

(ix) Glycerol           

(x) Sodium  Acetate

Q17.       Give account of chemical properties?

(i)  combustion of ethanol

(ii)  oxidation of ethanol

(iii)  reaction of C2H5OH with sodium  metal

(iv)  dehydration of C2H5OH

(v) reaction of C2H5OH with ethanoic acid

Q18.   An organic compound A with molecular formula C4H8O2 on alkaline hydrolysis gives two compound B and C. C on acidification with dil. HCl  gives   D. Oxidation of  B with K2Cr2O7/H2SO4 also gives  D. Identify A, B, C and  D and explain all the reactions involved.

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