CARBON AND ITS COMPOUNDS – 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?

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