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CBSE Questions for Class 11 Medical Chemistry Hydrocarbons Quiz 7 - MCQExams.com

Match the column I with Column II and mark the appropriate choice. 
Column I Column II
(A)nButane2Methylpropane(i)Free radical substitution
(B)CH4+Cl2hvCH3Cl(ii)Wurtz reaction
(C)RCOONa+SodalimeRH(iii)Isomerisation
(D)RX+NaetherRR(iv)Decarboxylation
  • (A)(iii),(B)(i),(C)(iv),(D)(ii)
  • (A)(ii),(B)(iv),(C)(i),(D)(iii)
  • (A)(i),(B)(ii),(C)(iv),(D)(iii)
  • (A)(iv),(B)(i),(C)(iii),(D)(ii)
Chlorination of alkanes is a photochemical process. It is initiated by the process of:
  • heterolysis
  • homolysis
  • pyrolysis
  • hydrolysis
The cycloalkane formed when 1,4dichloropentane is heated with sodium in presence of dry ether is ________.
  • methylcyclopentane
  • cyclopentane
  • methylcyclobutane
  • cyclobutane
Which one is incorrect name?
  • Propyne
  • But-2-yne
  • Pent-3-yne
  • But-1 -yne
Which one of the following IUPAC name is not correctly matched?
Ethane is formed during the formation of chloromethane by chlorination of methane because:
  • higher members of the hydrocarbons are generally formed during reactions
  • two methyl free radicals may combine during chlorination to give ethane
  • two chloromethane molecules react to form ethane
  • chlorine free radical reacts with methane to give ethane.
Finely divided platinum and palladium commonly known as platinum and palladium black, may be prepared by reducing their,soluble salts with:
  • H2O
  • C2H5OH
  • HCHO
  • C6H6
Cis-dicholoroethylene can be converted to trans-dicholorethylene by irradiations. During the interconversion.
  • Both the π and σ bonds are broken and reformed
  • Only the π bond is broken and reformed
  • The CCl and CH bonds are broken, H and Cl atoms interchanges their positions and new bonds are formed
  • Both the π and σ bonds rotate along with the groups
Which of the following has the lowest boiling point?
  • 2-Methylbutane
  • 2-Methylpropane
  • 2,2-Dimethylpropane
  • n-pentane
During halogenation of alkanes, the halogens and alkane show a specific trend. Which of the following statements is not correct?
  • The reactivity of halogens is in the order F2>Cl2>Br2>I2.
  • For a given halogen the reactivity of hydrocarbon is in the order of 3o>2o>1o.
  • Bromine is less reactive than chlorine towards a particular alkane.
  • On chlorination monosubstituted product is formed while on bromination disubstituted products are formed.
The heat of combustion of carbon to CO2 is -393.5 kJ/mol. The heat released upon formation of 35.2 g of CO2 from catbon and oxygen gas will be :
  • +315 kJ/mole
  • -31.5 kJ/mole
  • -315 kJ/mole
  • +31.5 kJ/mole
What is the carbon-carbon bond length in benzene?
  • 1.20˚A and 1.31˚A
  • 1.39˚A
  • 1.39˚A and 1.20˚A
  • 1.20˚A
Nitration and chlorination of benzene are:
  • nucleophilic and electrophilic substitution respectively
  • electrophilic and nucleophilic substitution respectively
  • electrophilic substitution in both the reactions
  • nucleophilic substitution in both the reactions.
Although benzene is highly unsaturated it does not undergo addition reactions. The explanation of this can be suggested as:
  • π-electrons of benzene ring are delocalised
  • since π-electrons are present inside the ring, addition cannot take place
  • cyclic structures do not show addition reactions
  • benzene is not a reactive compound.
What happens when calcium carbide is treated with water?
  • Ethane is formed.
  • Methane and ethane are formed.
  • Ethyne is formed.
  • Ethene and ethyne are formed.
Fill in the blanks with appropriate words. Benzene has a planar structure. All carbon atoms in benzene are I   hybridised. The ring structure of benzene was proposed by II . It shows III   substitution reactions. It reacts with IV  in presence of aluminium chloride to form acetophenone.
  • I=sp2II=KekuleIII=electrophilicIV=acetylchloride
  • I=spII=DewarIII=nucleophilicIV=chloromethane
  • I=sp3II=LadenbergIII=electrophilicIV=chloroethane
  • I=sp2II=BaeyerIII=nucleophilicIV=methylbromide
When n-butane is treated with chlorine, how many monochloro products are formed?
  • 1
  • 2
  • 3
  • 4
What is the order of reactivity of hydrogen atoms attached to the carbon atom in an alkane for free radical substitution?
  • 3o>1o>2o
  • 2o>1o>3o
  • 3o>2o>1o
  • 1o>2o>3o
One mole of 1,2-dibromopropane on treatment with X moles of NaNH2 followed by treatment with ethyl bromide gave a 2-pentyne. The value of X is:
  • one
  • two
  • three
  • four
Mark the incorrect statement from the following.
  • Benzene has a planar structure
  • Benzene is an unsaturated hydrocarbon and shows addition reactions like alkenes
  • In benzene carbon uses two p-orbitals for hybridisation
  • Aromatic hydrocarbons contain high percentage of carbon hence burn with sooty flame
The compound formed when an alcoholic solution of ethylene dibromide is heated with granulated zinc is:
  • ethene
  • ethyne
  • ethane
  • bromoethane
For the given Question (1,2,3)  consider the following reaction.
How many monohalo derivatives are possible (excluding stereoisomers) ?
988831_30338703deee44e296f4e5b4c0617e48.PNG
  • 3
  • 4
  • 5
  • 6
Halogenation is a substitution reaction, where halogen replaces one or more hydrogens of hydrocarbon.
Chlorine free radical make 1,2,3 radicals with almost equal ease, whereas bromine free radicals have a clear preference for the formation of tertiary free radicals. So , bromine is less reactive, and more selective whereas chlorine is less selective and more effective.
The relative rate of abstraction of hydrogen by Br is 
3(1600)>2(82)>1(1)
The relative rate of abstraction of hydrogen by Cl is 
3(5)>2(3.8)>1(1)
CH3CH3|C|CH3CH2CH3|CHCH3Br2/hvCH3CH3|C|CH3CH2CH2CH3|C|BrCH3
2,Bromo-2,5,5 trimethyl hexane(x%)
What is the value of x(% yield of product) ?


989068_91713f68b9d24a0abf9f18afe6d35729.png
  • 18 %
  • 82 %
  • 90 %
  • 60 %
Which of the following is aromatic in nature?
  • None of these
Select the chain propagation steps in the free-radical chlorination of methane.
(1)Cl_2\, \rightarrow 2Cl^{\cdot}
(2) Cl^\cdot \, + \, CH_4 \, \xrightarrow \, CH_3C1 \,+ \, H^\cdot
(3) C1^\cdot \, + \, CH_4 \, \xrightarrow \, CH_3 ^\cdot \, + \, HCI
(4) H^\cdot \, + \, Cl_2 \, \xrightarrow \, HCl+Cl^\cdot
(5) CH_3 ^\cdot \, + \, Cl_2 \, \xrightarrow \, CH_3CI+Cl^\cdot
  • 2,3,5
  • 1,3,6
  • 3,5
  • 2,3,4
Rank the transition states that occur during the following reaction steps in order of increasing stability (least \xrightarrow \,most stable)
1.H_3C \, - \, \overset{+}{OH_2} \, \xrightarrow \, CH_3^{+} \, + \, H_2O
2.(CH_3)_3C \, - \, \overset{+}{OH_2} \xrightarrow \, -  \,(CH_3)_3C \, + \, H_2O
3.(CH_3)_2 \, CH \, - \, \overset{+}{OH_2} \xrightarrow \,(CH_3)_2CH^+ \, + \, H_2O
  • 1 < 2 < 3
  • 2 < 3 < 1
  • 1 < 3 < 2
  • 2 < 1 < 3
n-Butane \xrightarrow{Cl_2/hv}
Give the total number of monochioro products (including stereoisomers), which are possible in the above reaction.
  • 2
  • 3
  • 4
  • 5
An alkane (mol.\ wt.\ = 86) on bromination gives only two monobromo derivatives (excluding stereoisomers). The alkane is:
  • CH_3-\underset{CH_3}{\underset{|}{C}}H-CH_2-CH_2-CH_3
  • CH_3-\overset{CH_3}{\overset{|}{\underset{CH_3}{\underset{|}{C}}}}-CH_2-CH_3
  • CH_3-\underset{CH_3}{\underset{|}{C}}H-\underset{CH_3}{\underset{|}{C}}H-CH_3
  • CH_3-\overset{CH_3}{\overset{|}{\underset{CH_3}{\underset{|}{C}}}}-CH_3
\xrightarrow[hv]{cl_2} (x). (x) = total number of di-chloro product S-2 chloro hexane.
988888_f6ed330ee37042ecbf37dcb4bf9cc698.png
  • 7
  • 6
  • 16
  • none
Arrange the following compounds in decreasing order of their heats of combustion:
989043_01290884912443bbbe16b1c559d8392c.png
  • (iii) > (ii) > (i)
  • (ii) > (i) > (iii)
  • (iii) > (i) > (ii)
  • (i) > (ii) > (iii)
Among the following free radical bromination reactions, select those in which 2 halide is the major product
989106_8724f21b495349fca893029e98f4f167.png
  • P, Q, R, S
  • P, R, U
  • P, R, S, T
  • P, Q, R, S, T
Which is not an aromatic compound?
  • Pyridine
  • Xylene
  • Naphthalene
  • Cyclohexane
Rank the hydrogen atoms (H_a, H_b, H_c) in the following molecules according to their acidic strengths:
989543_c38e05ac057f4cc69dff4800aebeef27.PNG
  • a > b > c
  • b > a > c
  • b > c > a
  • a > c > b
In this reaction SbF_5 acts as:
990372_d0f69e5ac8ca45d9855202e6bd7ee9ff.png
  • an acid
  • a base
  • a nucleophile
  • an electrophile
What is the final product (B)  of the sequence
992130_79d7a096ffb140e59a0153a673c44acc.png
In  order to prepare 1- chloro-propane which of the following reactants can be employed?
  • Propene and HCl in the presence of peroxide
  • Propene and Cl_2 followed by treatment with aq.KOH
  • Propanol-1 and SOCl_2/pyridine
  • Any of the above can be used
(A) \, + \, Cl_2 \, \xrightarrow {hv} \, monochloro \, product
To maximise the yield of monochloro product in the above reaction?
  • Cl_2 must be added in excess
  • Reactant (A) must be added in excess
  • Reaction must be carried out in dark
  • Reaction must be carried out with equimolar mixture of Cl_2 and A
Choose the appropriate product for this reaction.
993173_9dbf1a8768f441a2bc0a6b571f1d84ef.png
To carry our above conversion, (A) and (B) respectively, are :
989922_941fb2210cb54bea9adee178ae5f171c.png
  • NaNH_{2}, Cl - CH_{2} - CH_{2} - CH_{2} - Br
  • NaNH_{2}, F - CH_{2} - CH_{2} - CH_{2} - Br
  • NaNH_{2}, I - CH_{2} - CH_{2} - CH_{2} - Br
  • NaNH_{2}, I - CH_{2} - CH_{2} - CH_{2} - I
CH_3MgI will give methane with:
  • CH_3CH_3
  • CH_3-CH_2-NH_2
  • CH_3-CO-CH_3
  • all of these
In the reaction:
H-C\equiv CH\xrightarrow [ (i)NaNH_{ 2 }/Liq.NH_{ 3 } ]{ { (ii)CH_{ 3 }CH_{ 2 }Br } } X\xrightarrow [ (i)NaNH_{ 2 }/Liq.NH_{ 3 } ]{ { (ii)CH_{ 3 }CH_{ 2 }Br } } Y
X and Y are:
  • X=2-butyne, Y=2-hexyne
  • X=1-butyne, Y=2-hexyne
  • X=1-butyne, Y=3-hexyne
  • X=2-butyne, Y=3-hexyne
Reaction H-C\equiv C-H+HOCl\rightarrowproduct, here product will be:
  • ClCH_2-CHO
  • CHO-CHO
  • CH-Cl=CHCl
  • CHCl_2-CHCl_2
Using anhydrous AlCl_3 as catalyst, which one of the following reaction produces ethylbenzene (PhEt)?
  • H_2C=CH_2+C_6H_6
  • H_3C-CH_3+C_6H_6
  • H_3C-CH_2OH+C_6H_6
  • CH_3-CH=CH_2+C_6H_6
In the following sequence of reactions:
Toluene \overset{KMnO_4}{\rightarrow} A\overset{SOCl_2}{\rightarrow} B\overset{H_2/Pd}{\underset{BaSO_4}{\rightarrow}}C.
What is C?
  • Benzaldehyde
  • Benzoic acid
  • Benzoyl chloride
  • Acetophenone
IUPAC name of the compound is:
1007895_29cf3164ed09478880719e606288e358.png
  • butane
  • \gamma -Butane
  • cyclo-Butane
  • n-Butane
How will you prepare ethane from methyl chloride?
  • Williamson's synthesis
  • Wurtz synthesis
  • Hydrogenation of methyl chloride
  • Dehydrohalogenation of methyl chloride
Which of the following compound, on reaction with excess of RMgX, gives 3 moles of alkane (R-H)?
  • HC \equiv C -{\underset{OH}{\underset{|}{C}}H} - COOH
  • CH_3 - C \equiv C -{\underset{OH}{\underset{|}{C}}H} - COOH
  • HC \equiv C -{\underset{OCH_3}{\underset{|}{C}}H} - COOH
  • CH_2 = CH -{\underset{OH}{\underset{|}{C}}H} - COOH
The barrier for rotation about indicated bonds will be maximum in which of these compounds? 
1037090_4021236de9a44f5cb6849df8abc7627d.PNG
  • X
  • Y
  • Z
  • Same in all
The compound B formed in the following sequences of reactions is:
CH_3CH_2CH_2OH\overset{PCl_3}{\rightarrow}A\overset{Alc. KOH}{\rightarrow}B.
  • propyne
  • propene
  • propanol
  • propane
Write chemical equations for the preparation of following alcohols in the options starting from appropriate alkenes.
0:0:2


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