RBSE Class 11 Chemistry Important Questions Chapter 13 Hydrocarbons

Rajasthan Board RBSE Class 11 Chemistry Important Questions Chapter 13 Hydrocarbons Important Questions and Answers.

RBSE Class 11 Chemistry Chapter 13 Important Questions Hydrocarbons

Multiple Choice Type Questions:
 
Question 1. 
Reagent used in Sabatier Senderen reduction is. 
(a) H₂/Ni 
(b) Zn-Cu/C₂H₅OH 
(c) HI/P 
(d) LiAlH₄ 
Answer:
(d) LiAlH₄ 

 

Question 2. 
Which carbide is used in the formation of methane? 
(a) CaC₂ 
(b) Mg₂C₃ 
(c) Al₄C₃ 
(d) B₄C 
Answer:
(c) Al₄C₃ 

Question 3. 
On increasing number of carbon atoms in carbon chain the boiling point of alkane: 
(a) increases 
(b) decreases 
(c) unaffected 
(d) may increase or decrease 
Answer:
(a) increases 

Question 4. 
Which of the following on hydrolysis give methane? 
(a) Al₄C₃ 
(b) CaC₂ 
(c) nC₃H₇MgBr 
(d) Dry ice 
Answer:
(a) Al₄C₃ 

Question 5. 
Methane and ethane are formed in differen steps from: 
(a) C₂H₄ 
(b) CH₃I 
(c) CH₃OH 
(d) C₂H₅OH 
Answer:
(b) CH₃I 

Question 6. 
The best method for the formation methane: 
(a) Liquification of natural gas 
(b) Wurtz reaction 
(c) Reduction of CH₂Cl₂ 
(d) None of the above 
Answer:
(b) Wurtz reaction 

Question 7. 
The bond angle in CCl₄ is: 
(a) 90° 
(b) 109°
(c) 120° 
(d) 180° 
Answer:
(b) 109°

Question 8. 
How many secondary carbon atoms are present in isopentane? 
(a) 1 
(b) 2
(c) 3  
(d) 4 
Answer:
(a) 1 

Question 9. 
Which of the following compound does not dissolve on heating with conc. H₂SO₄? 
(a) Ethene 
(b) Benzene 
(c) Hexane 
(d) Aniline 
Answer:
(c) Hexane 

Question 10. 
The reactivity order of different hydrogen atoms attached with different carbon atoms of alkane is: 
(a) 3° 2° 1° 
(b) 1°> 2° > 3° 
(c) 3° 1° 2° 
(d) 2° 1° 3° 
Answer:
(a) 3° 2° 1° 

Question 11. 
Formation of alkane by the reaction of alkyl halide with zinc is known as : 
(a) Frankland reaction 
(b) Cannizzaro reaction 
(c) Wurtz reaction 
(d) Kolbe reaction 
Answer:
(a) Frankland reaction 

Question 12. 
When methyl bromide is heated with zinc in a closed vessel then we get: 
(a) methane 
(b) ethane
(c) ethene  
(d) methanol 
Answer:
(b) ethane

Question 13. 
In C₂H₆ the bond angle H-C-H is : 
(a) 90° 
(b) 109.5° 
(c) 120° 
(d) 180° 
Answer:
(b) 109.5° 

Question 14. 
Which of the following on reaction with Grignard reagent form hydrocarbon? 
(a) CH₃CH₂OH 
(b) CH₃CHO 
(c) CH₃COCH₃ 
(d) None of the above 
Answer:
(a) CH₃CH₂OH 

Question 15. 
Which of the following compound mainly show displacement reaction? 
(a) alkane 
(b) alkene 
(c) alkyne 
(d) all 
Answer:
(a) alkane 

Question 16. 
Which of the following show cracking? 
(a) Alkane 
(b) Petroleum 
(c) Ether 
(d) Benzene 
Answer:
(a) Alkane 

Question 17. 
The compound, whose aqueous solution on electrolysis give ethane, is: 
(a) Acetic acid 
(b) Acetamide 
(c) Potassium acetate 
(d) Ethyl acetate 
Answer:
(c) Potassium acetate 

Question 18. 
An example of halogenation of alkane is: 
(a) electrophilic substitution 
(b) nucleophilic substitution 
(c) free radical substitution 
(d) oxidation 
Answer:
(c) free radical substitution 

Question 19. 
The name of given reaction is 

(a) Alkylation 
(b) Cracking 
(c) Dehydrogenation 
(d) Distillation 
Answer:
(b) Cracking 

Question 20. 
The organic product formed from methyl magnesium bromide and ethyl alcohol is: 
(a) Methane 
(b) Ethane 
(c) Propane 
(d) Butane 
Answer:
(a) Methane 

Question 21. 
The product formed where 1-butene reacts with HBr is presence of methyl magnesium bromide is: 
(a) 1-bromo butane 
(b) 2-bromo butane 
(c) 1,2-dibromo butane 
(d) n-butane 
Answer:
(a) 1-bromo butane 

Question 22. 
The reaction in which alkene forms alcohol on reaction with water is known as: 
(a) hydrogenation
(b) hydration  
(c) hydrolysis 
(d) condensation 
Answer:
(b) hydration  

Question 23. 
Which of the following isomerism is not shown by alkene? 
(a) Chain isomerism 
(b) Geometrical isomerism 
(c) Metamerism 
(d) Position isomerism 
Answer:
(c) Metamerism 

Question 24. 
The general formula of alkene is: 
(a) C_nH_{2n + 1} 
(b) C_nH_2n 
(c) C_nH_{2n + 2} 
(d) C_nH_2n 
Answer:
(c) C_nH_{2n + 2} 

Question 25. 
Which type of hybridisation is present in 1-2 carbon of propylene? 
(a) sp 
(b) sp² 
(c) sp³ 
(d) None 
 Answer:
(d) None 
 
Question 26. 
The C-C-C bond angle in CH₃-CH=CH₂ is: 
(a) 90°
(b) 109.5° 
(c) 120° 
(d) 180° 
Answer:
(c) 120° 

Question 27. 
Which of the following alkene show geometrical isomerism? 
(a) 1-butene 
(b) 2-butene 
(c) 2-methyl propene 
(d) Propene 
Answer:
(b) 2-butene 

Question 28. 
The compound formed on dehydrohalo-genation of ethylene dibromide is: 
(a) Ethene 
(b) Ethyne 
(c) Butyne 
(d) Propyne 
Answer:
(b) Ethyne 

Question 29. 
Ethylene is the member of series: 
(a) alkyne 
(b) olefins 
(c) paraffin 
(d) amine 
Answer:
(b) olefins 

Question 30. 
Whose dehydrase form ethylene? 
(a) CH₃OH
(b) C₂H₅OH  
(c) propyl alcohol 
(d) ethyl acetate
Answer:
(b) C₂H₅OH  

Question 31. 
When ethyl alcohol is heated with conc. H₂SO₄ then we get: 
(a) CH₃COOC₂H₅ 
(b) C₂H₆ 
(c) C₂H₄ 
(d) C₂H₂ 
 Answer:
(b) C₂H₆ 
 
Question 32. 
Which decolourise aqueous KMnO₄ solution? 
(a) C₃H₈ 
(b) C₂H₄ 
(c) CH₄ 
(d) CCl₄
Answer:
(b) C₂H₄ 

Question 33. 
The reaction of ethylene with hydrogen bromide is an example of: 
(a) Addition reaction 
(b) Condensation reaction 
(c) Substitution reaction 
(d) Polymerisation reaction 
Answer:
(a) Addition reaction 

Question 34. 
The compound which easily decolourise potassium permanganate solution is: 
(a) CH₃CH₃ 
(b) C₁₀H₁₈ 
(c) (CH₃)₄ 
(d) CH₃CH 
Answer:
(d) CH₃CH 

Question 35. 
CH₃CH = CHCHO can be oxidised CHCH₃ into CH₃CH=CH-CH by the action of: 
(a) Alkaline KMnO₄ 
(b) Ammonical silver nitrate 
(c) Selenium dioxide 
(d) Osmium tetraoxide 
Answer:
(b) Ammonical silver nitrate 

Question 36. 
The angle H-C-H in ethene is: 
(a) 90° 
(b) 60° 
(c) 180° 
(d) 120° 
Answer:
(d) 120° 

Question 37. 
In ethylene C-C bond has: 
(a) Тwо л-bоnds 
(b) One sigma and one л-bond 
(c) Two sigma bonds 
(d) One sigma and two л bonds 
Answer:
(b) One sigma and one л-bond 

Question 38. 
How many structural isomers are possible in C₄Hg? 
(a) 2 
(b) 3 
(c) 4 
(d) 5 
Answer:
(c) 4 

Question 39. 
How many isomers 2-butene have? 
(a) 1 
(b) 2 
(c) 3 
(d) 4 
Answer:
(b) 2 

Question 40. 
The C-H bond energy in ethane, ethylene and acelylene series is : 
(a) Similar in all the three compounds 
(b) Maximum in ethane 
(c) Maximum in ethylene 
(d) Maximum in acelylene 
Answer:
(d) Maximum in acelylene 

Question 41. 
A gas do not give any precipitate when passed through ammonical AgNO₃ solution, but can decolourise alkaline solution. The gas is KMnO₄ 
(a) C₂H₆ 
(b) C₂H₄ 
(c) C₂H₂ 
(d) C₃H₈ 
Answer:
(b) C₂H₄ 

Question 42. 
Nitration of benzene is : 
(a) Nucleophilic substitution reaction 
(b) Electrophilic substitution reaction 
(c) Nucleophilic addition 
(d) Electrophilic addition 
Answer:
(b) Electrophilic substitution reaction 

Question 43. 
Number of σ and π-electrons in benzene are: 
(a) 24-σ and 6 - л electrons 
(b) 12-σ and 6-π electrons 
(c) 12-σ and 3- л еlectrons 
(d) 24-σ and 3 - π electrons 
Answer:
(c) 12-σ and 3- л еlectrons 

Question 44. 
Which of the following strongest meta directing group? 
(a) -NO₂ 
(b) -SO₃H 
(c) -CHO 
(d) -COOH
 Answer:
(a) -NO₂ 
 
Question 45. 
Number of double bonds in BHC is: 
(a) 1
(b) 2  
(c) 3 
(d) 0 
Answer:
(d) 0 

Question 46. 
The work of dry aluminium chloride Friedel Craft reaction is: 
(a) To absorb water 
(b) To absorb HCl 
(c) To create electrophilic 
(d) To create nucleophilic 
Answer:
(c) To create electrophilic 

Question 47. 
The mixture of sodium benzoate sodalime on heating give: 
(a) Benzene 
(c) Sodium benzoate 
(b) Methane 
(d) Calcium benzoate 
Answer:
(a) Benzene 

Question 48. 
In the reaction, 

Tribromobenzene, here 'X' is: 
(a) Benzoic Acid 
(b) Salicylic acid 
(c) Phenol 
(d) Aniline 
Answer:
(d) Aniline 

Question 49. 
Phenol on distillation with Zn-Power gives : 
(a) C₆H₆ 
(b) C₆H₅-C₆H₅ 
(c) C₆H₁₂ 
(d) C₆H₅-0-C₆H₅ 
Answer:
(a) C₆H₆ 

Question 50. 
The most reactive compound for electrophilic nitration is: 
(a) Benzene 
(b) Nitrobenzene 
(c) Benzoic Acid 
(d) Toluene 
Answer:
(d) Toluene 
 
Very Short Answer Type Questions:
 
Question 1. 
All the bonds in methane are same. Why? 
Answer:
Because the carbon atom in methane is sp hybridised and all the C-H bonds are formed b overlapping between sp³-s orbitals. 

Question 2. 
Yet the electronegativity of F is higher tha Cl, but the dipole moment of CH₃Cl is highe than CH₃F. Why? 
Answer: 
Because the bond length of C-Cl bond is highe than C-F bond. 

Question 3. 
Neopentane give only one type of mon substituted isomer. Why? 
Answer: 
Because all the hydrogen atom (H) present i neopentane are similar i.e., 1° type. 

Question 4. 
Write the formula of n-pentane, isobutane and neopentane. 
Answer: 

Question 5. 
Represent 1°, 2° and 3° hydrogen atoms in 2-methyl butane. 
Answer: 

Question 6.
What is decarboxylation? 
Answer: 
Removal of CO₂ from a compound is known as decarboxylation. 

Question 7. 
Write the name of gaseous products formed at anode on electrolysis of aqueous solution of sodium acetate. 
Answer: 
On electrolysis of aqueous solution of sodium acetate we get C₂H₆ and CO₂ gas at anode. 

Question 8. 
Which have higher boiling point among n-pentane and iso-pentane and why? 
Answer: 
n-pentane has higher boiling point because it - has higher surface area. 

Question 9. 
Why any alkane is reformed? 
Answer: 
To increase the octane number of any alkane, it ) is reformed. Reformation is done at very high temperature and high pressure (28-50 atm). 

Question 10. 
How many secondary carbon atoms are present in 2, 2-dimethyl butane? 
Answer: 

Question 11. 
The reactivity of alkane is lower than alkene and alkyne. Why? 
Answer: 
In alkanes the C-C and C-H bonds are non-polar in nature because of this reason the n attacking species can not attack on it. While in case of r double and triple bond л-electrons present on it, can attract the attacking species E easily. Hence the  reactivity of alkane is lower than alkenes and alkynes. 

Question 12. 
Write the name of reagent which is used in decarboxylation reaction of -COOH group. 
Answer: 
Soda lime (NaOH + CaO) 
 
Question 13. 
Ethene can be dried by concentrated H₂SO₄ but amine cannot, why? 
Answer: 
Because ethene is absorbed by conc. H₂SO₄ and A ethylene hydrogen sulphate is formed. 

Question 14. 
Write the name of products formed by the cracking of n-butane. 
Answer: 

Question 15. 
When secondary butyl bromide is treated with alcoholic KOH then different types of alkenes are formed. Write the name of these alkenes and which one is major. 
Answer: 
When secondary butyl bromide is heated with Ar alcoholic KOH then the mixture of 1-butene and be 2-butene is formed in which 2-butene is major. 

Question 16. 
Write how much s-character is present in = C-H (sp-s) bond of alkynes? 
Answer:
50% s-character. 

Question 17. 
How many unhybridised p-orbitals are present on each carbon atom of triple bond. 
Answer: 
Two unhybridised p-orbitals i.e., p, and p₂. 

Question 18. 
How many bonds are formed by lateral or sidewise overlapping of the two unhybridised p-orbitals of carbon atoms having triple bond? 
Answer: 
Two-л bоnds are formed. 

Question 19. 
What type of three dimentional position of both the bonds present in triple bond have? 
Answer: 
Both the p-orbitals present on each carbon form 90° with respect to each other and with respect to sp-hybridised orbitals. 

Question 20. 
All the four lobes of both T-bonds exist in which form about the internuclear axis? 
Answer: 
Electron cloud between two carbon atoms is Ar cylindrically symmetrical about the internuclear axis. 

Question 21. 
Which compound is formed when CHI is reacted with silver? 
Answer: 
Acetylene. 

Question 22. 
What compound is formed when acetylene is passed through ammonium silver nitrate solution? 
 Answer: 
 Silver acetylide is formed.

Question 23. 
Which bipolymerisation compound is formed  of acetylene? 
Answer: 
Vinyl acetylene. 

Question 24. 
Which compound is formed by tripolymerisation of propyne ? 
Answer:
Mesitylene. 

Question 25. 
What is the name of artificial rubber? 
Answer: 
Neoprene rubber. 

Question 26. 
Which compound is formed by carboxylationof acetylene? 
Answer:
Acrylic Acid 

Question 27. 
Which compound is formed when the oxidation of C₂H₂ is done with chromic acid? 
Answer: 
Acetic acid 

Question 28. 
Yet the bond energy of C-H bond in acetylene is higher than C-H bond of alkane and alkene, but acetylene is acidic, why? 
Answer: 
The polarity of C-H bond of acetylene is higher cause this bond is formed by overlapping of sp ybridised orbitals and s-orbitals, and sp-hybridised bitals are more electronegative than sp³- and sp ybridised orbitals. 

Question 29. 
Ortho and para directing group increases the activity of nucleus of benzene. Why? 
Answer: 
These groups are electron releasing hence their esence increases the electron density on the nzene nucleus, which increases its activity.
 
Question 30. 
Who first time used the word aromatic? 
Answer: 
Kekule. 

Question 31. 
A compound burns with smoky flame. What is its nature? 
Answer: 
Aromatic. 

Question 32. 
What is the bond length of C-C bond in benzene? 
Answer: 
1.39 Å 

Question 33. 
What are aromatic non-benzenoid compounds? 
Answer: 
Those aromatic compounds which do not have nzene nucleus are called non-benzenoid aromatic molecules.
 
Question 34. 
Write two examples in which aromatic compounds do not have benzene nucleus. 
Answer:

Question 35. 
Write two examples of aliphatic compounds which burns with smoky flame? 
Answer:
CHCl₃, CCl₄. 

Question 36. 
Write one example of aromatic compound which do not burn with smoky flame. 
Answer:
Benzyl alcohol. 

Question 37. 
What is arene? 
Answer:
Aromatic hydrocarbon. 

Question 38. 
What are heterocyclic aromatic compounds? 
Answer: 
Those aromatic compounds whose ring have any hetero atom. For example pyridine. 

Question 39. 
Which type of reactions are given by aromatic compounds? 
Answer:
Generally electrophilic substitution reactions. 

Question 40. 
Who discovered Benzene? 
Answer: 
Michael Faraday.
 
Question 41. 
What is B.H.C.? 
Answer: 
Benzene hexa chloride (B.H.C.) is an insecticide 

Question 42. 
Why alkenes show geometrical isomerism? 
Answer: 
Alkenes have π-bond. In π-bond rotation around π-bond is not possible i.e., rotation around bond i restricted. Hence they show show geometrica isomerism. 

Question 43. 
Unsaturated hydrocarbons are more reactive than saturated hydrocarbons. Why? 
Answer: 
All the alkanes have strong C-C sigma bond and C-H bond is also strong and less polar in nature While alkenes are more reactive due to the presence of л bond in C-C bond. 

Question 44. 
A hydrocarbon (A) having two carbon atons can decolourise 1 percent alkaline potassium permanganate solution but it does not reac with ammonical silver nitrate solution. Write the name and structural formula o compound (A). 
Answer: 
Hydrocarbon (A) decolourise alkaline KMnO hence it is unsaturated. As it does not react with ammonical AgNO₃ hence it is ethelene not acetylene as it has only two carbon atom, hence (A) is 
CH₂ = CH₂ 

Question 45. 
Arrange the following alkene in decreasing order of their stability. 

Answer: 
Stability order I > III > II 

Question 46. 
The formula of hydrocarbon is C₃H₆. Write its structure if 
(i) It decolourises the Baeyer's reagent. 
(ii) It can not decolourise Baeyer's reagent. 
Answer: 

Question 47. 
Write the formula of mustard gas. 
Answer:

Questionn 48. 
CH₂=CH is more basic than HC = C- Why? 
Answer: 
Because its conjugate acid CH₂ = CH₂ is less acidic than CH = CH. 

Question 49. 
Write the name of first three members of acetylene series. 
Answer: 
C₂H₂, C₃H₄, C₄H₆. 

Question 50. 
What is -C- C-Bond is known? 
Answer: 
Acetylene bond. 

Question 51. 
An hydrocarbon (A) having two carbon atoms and decolourises the Baeyer's reagent. When it is passed through Cu₂Cl₂/NH4OH then it gives precipitate. What is its nature? 
Ans: 
It is acetylene and have triple bond [CH=CH]. 

Question 52. 
Arrange ethane, ethene and ethyne in increasing order of their acidic behaviour. 
Answer: 

Question 53. 
What are the main component of Colour gas? 
Answer: 
n-butane and isobutane. 

Question 54. 
Write one reaction which proves that acidic nature of acetylene. 
Answer: 
It gives acetylide with sodium. 

Question 55. 
Draw all the possible isomers of C₂H₂Cl₂. Which one is non polar in it ? 
Answer: 

Isomer (II) is non polar in nature. 

Question 56. 
Staggered and eclipsed conformers of ethane cannot be separated at normal temperature. Why? 
Answer: 
There is very less difference in the energies of both the conformers hence they cannot be separated at normal temperature. 

Question 57. 
Concentrate H₂SO₄ is used to dry ethane not to ethene, why? 
Answer: 
Because ethane does not react with conc. H₂SO₄. But ethene forms ethyl hydrogen sulphate with conc. H₂SO₄· 

Question 58. 
How ethane is formed during chlorination of methane? 
Answer: 
When the chlorination of methane is done then free radicals are formed. These free radicals react with each other and form ethane. This is termination step. 

Question 59. 
Why nitro benzene do not give Friedel craft reaction? 
Answer: 
In nitro benzene-NO₂ group is attached with carbon ring and deactivate the benzene ring in such a way that the alkylation by CH⁺₃ and acylation by CH₃CO⁺ group is not possible. 

Question 60. 
How many sigma and pi bonds are present in one molecule of benzene. 
Answer: 

Total o bonds = 12, л bonds = 3 

Question 61. 
2-Butene has two geometrical isomers while 1-butene do not. Why? 
Answer: 
In 2-butene both the carbon atom attached with double bond have different groups. While in 1-butene one carbon atom is satisfied by two hydrogen atom. Hence 1-butene cannot show geometrical isomer while 2-butene have 

Short Answer Type Questions:
 
Question 1. 
Convert the following: 
(i) Methane from ethyne 
(ii) Ethyne from ethene 
(iii) Ethyne from ethene 
(iv) 2-Butyne from ethyne 
Answer: 
(1) Methane from ethyne: 

(2) Ethyne from ethene: 

(3) Ethyne from ethane: 

(4) 2-Butyne from ethyne: 

Question 2. 
Differentiate between aromatic and aliphatic compounds. 
Answer:

Aromatic Compounds	Aliphatic Compounds
1. These are closed chain compounds.	1. These are open chain compounds.
2. They have higher percentage of carbon.	2. They have low percentage of carbon.
3. They burn with smoky flame.	3. They do not bum with smoky flame.
4. These give replacement reactions easily.	4. These do not give replacement reactions.
5. Their hydroxy compounds are acidic in nature.	5. Their hydroxy compound are neutral.
6. Their halogen derivatives are less reactive.	6. Their halogen derivatives are highly reactive.

Question 3. 
Identify 1°, 2° and 3° carbon atoms in given alkane: 
CH₂ - CH₂ - C(CH₃)₂ - CH2 - CH(CH3)2 
Write the number of total hydrogen atoms attached to each carbon atom. 
Answer: 
If carbon atom is attached with one hydrogen -oms then this carbon atom is known as 1o carbon atom. 

If carbon atom is attached with two hydrogen atom then this carbon atom is known as 2° carbon atom. If carbon atom is attached with three hydrogen ato then it is known as 3° carbon atom. 

Number of 1° Hydrogen atom = 5 
Number of 2° hydrogen atom = 4 
Number of 3° hydrogen atom = 1 

Question 4. 
What happens when (Write only chemica reaction): 
(i) Propane reacts with SO₂ and Cl₂ presence of sunlight? 
(ii) Ethyl iodide reacts with red phosphoru and HI? 
(iii) Methyl bromide reacts with sodium presence of dry ether? 
(iv) n-Butane is heated in presence anhydrous AlCl₃? 
(v) Sodium acetate is heated with mixture NaOH and CaO? 
Answer: 
(i) Propane sulphuryl chloride is formed. 

(ii) Ethane is formed 

 
(iii) Ethane is formed 

 
(iv) Isobutane is formed 

(v) Methane is formed. 

Question 5. 
Predict the product of the following reaction: 

Answer: 
Electrophillic addition occurs through the more stable carbocation intermediate: 

Question 6. 
Write down one-one example of each reaction only reaction. 
(i) Decarboxylation 
(ii) Clemmensen reduction 
(iii) Catalytic reformation 
(iv) Thermal Cracking 
(v) Wurtz reaction 
Answer: 
(i) Decarboxylation: 

(ii) Clemmensen reduction: 

(iii) Catalytic reformation: 

(iv) Thermal Cracking: 

(v) Wurtz Reaction: 

Question 7. 
How will you get. 
(1) Mustard gas 
(2) Lewisite? 
Answer: 
(1) Mustard gas: 
When ethylene reacts with sulphur monochloride then mustard gas is formed. 

(2) Lewisite: When reacts with arsenictri chloride in presence of anhydrous AlCl₃ then Lewisite is formed. 

Question 8. 
Check the aromaticity of following structures 

Answer: 
According to Huckel's rule those compounds are aromatic in which (4n + 2)л electrons participate in delocalisation. (These electrons can be lone pair also) 
(here n = 0, 1, 2 any whole number). 
(1) 

here number of delocalised л electrons are 4 + 2 = 6 
According to Huckel issule (4 × 1 + 2) = 6 hence it is aromatic. 

(2) 

here number of delocalised e 5 × 2 = 10π 
According to Huckel's rule (4 × 2 + 2) = 10π hence it is aromatic. 

(3) 

number of e participating in delocalisation is: = 4+2=6 
According to Huckel's rule (4 ×1+ 2) = 6 so it is also aromatic. 

(4) 

number of e participating in delocalisation = 4 
According to Huckel's (4 ×1+ 2) = 6 Hence it is not aromatic. 

Question 9. 
What are cancer creating and poisonous compounds. Explain with example? 
Answer: 
Benzene and polynucleur hydrocarbons in which more than two benzene rigngs are joined, known as cancer creating and poisonous organic compounds. 
Example: 

Competitive Exam Questions:
 
Question 1. 
The sodium product obtained when methoxide reacts, with 2-chloro-2-methyl pentane in methanol, is: 

(a) (A) and (C) 
(b) Only (C) 
(c) (A) and (B) 
(d) All of above 
Answer: 
(c) (A) and (B) 

Question 2. 
The reagent used in Wolff Kishner reduction is: 
(a) NH₂-NH₂ and KOH in ethylene glycol 
(b) Zn-Hg/Conc. HCl 
(c) Con. HNO₃ 
(d) Potassium dichromate and dil H₂SO₄ 
Answer: 
(b) Zn-Hg/Conc. HCl 

Question 3. 
Which of the following give good yield of primary nitro alkane with the help of oxidised aldoxime? 
(a) Trifluoro peroxy acetic acid 
(b) Acidified potassium permanganate 
(c) Conc. HNO 
(d) Potassium dichromate & dil. H₂SO₄·
Answer: 
(a) Trifluoro peroxy acetic acid 
 

Question 4. 
The hydrocarbon, in which five carbon atoms with one methyl group is attached in a chain, can form derivative. 
(a) 2 
(b) 3 
(c) 4 
(d) 5 
Answer: 
(b) 3 

Question 5. 
The petrol with octane number 80 have: 
(a) 20% n-heptane + 80% iso-octane 
(b) 80% n-heptane + 20% cyclo-octane 
(c) 20% n-heptane + 80% n-octane 
(d) 80% n-heptane + 20% n-octane
Answer: 
(d) 80% n-heptane + 20% n-octane
 
Question 6. 
Which of the following compound give methane on reaction with water? 
(a) Al₄C₃ 
(b) CaC₂ 
(c) VC 
(d) Sic 
(e) B₄C 
Answer: 
(a) Al₄C₃ 

Question 7. 
An example of halogenation of alkane is: 
(a) Electrophilic substitution 
(b) Nucleophilic substitution 
(c) Free radical substitution 
(d) Oxidation 
Answer: 
(c) Free radical substitution 

Question 8. 
Which branched chain isomer of hydrocarbon having molecular weight 724 will give only one isomer of mono substituted alkyl halide? 
(a) Tertiary butyl chloride 
(b) Neopentane 
(c) Isohexane 
(d) Neohexane 
Answer: 
(b) Neopentane 

Question 9. 
Which of the following have largest C-H bond length? 
(a) C₂H₂ 
(b) C₂H₄
(c) C₂H₆ 
(d) C₂H₂ Br₂ 
Answer: 
(d) C₂H₂ Br₂ 

Question 10. 
Which has minimum boiling point? 
(a) 1-butene 
(b) 1-butyne 
(c) n-butane 
(d) isobutane 
Answer: 
(a) 1-butene 

Question 11. 
Which of the following has maximum boiling point? 
(a) n-butane 
(b) iso-octane 
(c) n-octane 
(d) 2, 2, 3, 3-tetra methyl butane 
Answer: 
(b) iso-octane 

Question 12. 
n-hexadecane have octane number: 
(a) 90 
(b) 100 
(c) 110 
(d) 0 
Answer: 
(c) 110 

Question 13. 
Which have minimum boiling point? 
(a) 2-methyl butane 
(b) 2-methyl propane 
(c) 2,2-dimethyl propane 
(d) n-pentane 
(e) n-butane 
Answer: 
(a) 2-methyl butane 

Question 14. 
The correct order of boiling point of 2, 2-dimethyl propane, 2-methyl butane and n-pentane is: 
(a) n-pentane > 2, 2-diethyl propane > 2-methyl butane 
(b) n-pentane > 2-methyl butane > 2, 2-dimethyl prpopane 
(c) 2,2-dimethyl propane > 2-methyl butane > n-pentane 
(d) 2-methyl butane > 2, 2-dimethyl propane > n-pentane 
Answer: 
(b) n-pentane > 2-methyl butane > 2, 2-dimethyl prpopane

Question 15. 
An alkane gives only one monochloro alkane when reacts with Cl₂ in presence of UV light. The alkane is: 
(a) Propane 
(b) Pentane 
(c) Isopentane 
(d) Neopentane 
Answer: 
(c) Isopentane 

Question 16. 
An alkene gives only one type of dicarbonyl compound on ozonolysis. The structure of alkene is: 

Answer: 

Question 17. 
The product obtained on ozonolysis, and then reduction by Zn and H₂O, of 2, 3-dimethyl-1-Butene will be. 
(a) Methanoic acid and 2-methyl-2-butanol 
(b) Methanal and 3-methyl-2-butanol 
(c) Methanol and 2,2-dimethyl 3-butanone 
(d) Methanoic acid and 2-methyl-3-butanone 
Answer: 
(a) Methanoic acid and 2-methyl-2-butanol 

Question 18. 
The molecular of Willkinson's catalyst used during hydrogenation of alkene is : 
(a) CO(CO)₈ 
(b) [(Pb₃P)₃ RhCl]
(c) [Pt(NH₃)₂Cl₂] 
(d) K[Ag(CN)₂] 
Answer: 
(b) [(Pb₃P)₃ RhCl]

Question 19. 
The formula of that compound which reacts easily with gaseous bromine is: 
(a) C₂H₄ 
(b) C₃H₆ 
(c) C₂H₂ 
(d) C₄H₁₀ 
Answer: 
(d) C₄H₁₀ 

Question 20. 
The correct order of enthalpy of hydrogenation of following compound is : 

(a) III > II > I 
(b) II > III > I 
(c) II > I > III 
(d) I > II > III. 
Answer: 
(c) II > I > III 

Question 21. 
The main product of following reaction is 

Answer: 

 
Question 22. 
The product 'C' is in the following reaction is 

(a) Acetaldehyde
(b) Acetylene  
(c) Ethylene 
(d) Acetyl Chloride 
Answer: 
(d) Acetyl Chloride 

Question 23. 
The 'Z' is 

(a) CH₃(CH₂)₄ - O - CH₃ 
(b) CH₃CH₂ - CH(CH₃) - OCH₂CH₃ 
(c) CH₃ (CH₂)₃ - O - CH₂CH₃ 
(d) (CH_n)₂ CH₂ - O - CH₂CH₃
Answer:  
(b) CH₃CH₂ - CH(CH₃) - OCH₂CH₃ 

Question 24. 
Which of the following do not use as gaseous fuel? 
(a) Gasoline 
(b) Acetylene 
(c) Carbon monoxide 
(d) Ethane 
Answer: 
(a) Gasoline 

Question 25. 
Which of the following do not show Anti Markownikoff's rule of HBr? 
(a) Propene
(b) But-1-ene  
(c) But-2-ene 
(d) Pent-2-ene 
Answer: 
(b) But-1-ene  

Question 26. 
One mole alkene on ozonolysis forms one mole proponone and one mole formaldehyde. The alkene is: 
(a) 2-methyl propene 
(b) 2,2-dimethyl-1-butene 
(c) Propene 
(d) 2-butene 
(e) 1-butene 
Answer:
(c) Propene  

Question 27. 
Which is the most stable alkene? 
(a) R₂C = CR₂
(b) RCH = CHR  
(c) RCH = CR₂ 
(d) CH₂ = CH₂ 
Answer: 
(d) CH₂ = CH₂ 

Question 28. 
Alkene R-CH CH₂ and B₂H₆ reacts rapidly with, each other. The product obtained on oxidation of its product by alkaline H₂O₂ will be: 
(a) RCH₂CHO 
(b) H-CH₂-CH₂-OH 
(c) RCOCH₃ 
(d) R-CH-CH-CH₃ 
Answer: 
(a) RCH₂CHO 

Question 29. 
The product obtained when hex-1-ene reacts with HBr in presence of benzoyl peroxide is: 
(a) 2-bromohexane 
(b) 2, 3-dibromohexane 
(c) 1, 2-dibromo hexane 
(d) 2, 4-diboromohexane 
(e) 1-bromohexane 
Answer: 
(d) 2, 4-diboromohexane 

Question 30. 
The alkene which on ozonolysis form acetone is: 
(a) CH₂ = CH₂
(b) CH₃CH = CH₂ 
 (c) (CH₃)₂C = C(CH₃₎₂ 
(d) CH₃-CH = CH-CH₃ 
Answer: 
(a) CH₂ = CH₂

Question 31. 
The main product is the reaction is, 

Answer: 

Question 32. 
The reaction is: 
CH₂ CH - CH₃ + HBr → CH₃ CHBr - CH: 
(a) Electrophilic addtion 
(b) Nucleophilic addition 
(c) Electrophilic substitution 
(d) Free radical addition reaction 
Answer: 
(d) Free radical addition reaction 

Question 33. 
Which of the following pair do not show cyclic compound of C₄H₆? 

Answer: 

Question 34. 
In reaction,
Y, X and Y are: 
(a) X = 1-butyne, Y = 3-hexyne 
(b) X = 2-butyne Y = 3-hexyne 
(c) X = 2-butyne Y = 2-hexyne 
(d) X = 1-butyne Y = 2-hexyne 
Answer: 
(a) X = 1-butyne, Y = 3-hexyne 

Question 35. 
In Pyrrole 

the electron density is maximum at: 
(a) 2 & 5 
(b) 2 & 3 
(c) 3 & 4
(d) 2 & 4 
Answer: 
(a) 2 & 5 

Question 36. 
In the following reaction, 

The product 'P' will not give: 
(a) Tollen's Reagent Test 
(b) Predy's Reagent Test 
(c) Victor Mayer's Test 
(d) Iodoform Test 
Answer: 
(c) Victor Mayer's Test 

Question 37. 
Which has acidic hydrogen? 
(a) Ethyne 
(b) Ethene 
(c) Ethane 
(d) Benzene 
Answer: 
(a) Ethyne 

Question 38. 
Acetylene give? 
(a) White ppt with AgNO₃ and red ppt with Cu₂Cl₂ 
(b) White ppt with Cu₂Cl₂ & red ppt with AgNO₃ 
(c) White ppt with both reagents 
(d) Red ppt with both reagents 
Answer: 
(a) White ppt with AgNO₃ and red ppt with Cu₂Cl₂ 

Question 39. 
Which is not related to Friedel Craft's reaction? 
(a) Sulphonation 
(b) Nitration 
(c) Acylation 
(d) Reduction 
Answer: 
(d) Reduction 

Question 40. 
Which of the one following is benzenoid aromatic compound? 
(a) Furan 
(b) Thiophene 
(c) Pyridine 
(d) Aniline 
Answer: 
(d) Aniline 

Question 41. 
The product 'P' is: 

Answer: 

Question 42. 
The total number of aromatic compounds formed from the following reaction is: 

(a) Zero 
(b) Two 
(c) Three 
(d) Four 
Answer: 
(c) Three 

Question 43. 
Benzene on reaction with Me₃COCl in presence of AICl₃ gives: 

Answer: 

Question 44. 
free radical is aromatic because it have: 
(a) 6π-orbital and 7 unpaired e- 
(b) 6π-orbital and 6 unpaired e- 
(c) 7p-orbital and 6 unpaired e- 
(d) 7p-orbital and 7 unpaired e- 
Answer: 
(b) 6π-orbital and 6 unpaired e- 

Question 45. 
Which of the following molecule is unstable at room temperature? 

Answer: