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)$$n-Butane \rightarrow 2-Methylpropane$$(i)Free radical substitution
(B)$$CH_4+Cl_2\xrightarrow [  ]{ hv }  CH_3Cl$$(ii)Wurtz reaction
(C)$$RCOONa + Soda\,lime \rightarrow RH$$(iii)Isomerisation
(D)$$RX + Na \xrightarrow [  ]{ ether }  R-R$$(iv)Decarboxylation
  • $$(A)\rightarrow (iii) ,(B)\rightarrow(i) , (C)\rightarrow (iv),(D)\rightarrow (ii)$$
  • $$(A)\rightarrow (ii) ,(B)\rightarrow(iv) , (C)\rightarrow (i),(D)\rightarrow (iii)$$
  • $$(A)\rightarrow (i) ,(B)\rightarrow(ii) , (C)\rightarrow (iv),(D)\rightarrow (iii)$$
  • $$(A)\rightarrow (iv) ,(B)\rightarrow(i) , (C)\rightarrow (iii),(D)\rightarrow (ii)$$
Chlorination of alkanes is a photochemical process. It is initiated by the process of:
  • heterolysis
  • homolysis
  • pyrolysis
  • hydrolysis
The cycloalkane formed when $$1,4-dichloropentane$$ 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:
  • $$H_{2}O$$
  • $$C_{2}H_{5}OH$$
  • $$HCHO$$
  • $$C_{6}H_{6}$$
Cis-dicholoroethylene can be converted to trans-dicholorethylene by irradiations. During the interconversion.
  • Both the $$\pi$$ and $$\sigma$$ bonds are broken and reformed
  • Only the $$\pi$$ bond is broken and reformed
  • The $$C-Cl$$ and $$C-H$$ bonds are broken, $$H$$ and $$Cl$$ atoms interchanges their positions and new bonds are formed
  • Both the $$\pi$$ and $$\sigma$$ 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 $$F_2>Cl_2>Br_2>I_2$$.
  • For a given halogen the reactivity of hydrocarbon is in the order of $$3^o>2^o>1^o$$.
  • 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 $$C{O}_{2}$$ is -393.5 kJ/mol. The heat released upon formation of 35.2 g of $$C{O}_{2}$$ 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?
  • $$ 1.20 \mathring { A }$$ and $$1.31 \mathring { A } $$
  • $$ 1.39 \mathring { A } $$
  • $$ 1.39 \mathring { A }$$ and $$ 1.20 \mathring { A } $$
  • $$ 1.20 \mathring { A } $$
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:
  • $$\pi$$-electrons of benzene ring are delocalised
  • since $$\pi$$-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.
  • $$ I = sp_2 \,\,\, II = Kekule \,\,\, III= electrophilic \,\,\, IV = acetyl\, chloride$$
  • $$ I = sp \,\,\, II = Dewar \,\,\, III= nucleophilic \,\,\, IV =chloromethane$$
  • $$ I = sp_3 \,\,\, II = Ladenberg \,\,\, III= electrophilic \,\,\, IV = chloroethane$$
  • $$ I = sp_2 \,\,\, II = Baeyer \,\,\, III= nucleophilic \,\,\, IV = methyl\, bromide$$
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?
  • $$3^o >1^o >2^o$$
  • $$2^o >1^o >3^o$$
  • $$3^o >2^o >1^o$$
  • $$1^o >2^o >3^o$$
One mole of 1,2-dibromopropane on treatment with $$X$$ moles of $$NaNH_2$$ 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 $$1^{\circ} ,2^{\circ} ,3^{\circ}$$ 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 
$$\underset{(1600)}{3^\circ} \, > \, \underset{(82)}{2^\circ} \, > \, \underset{(1)}{1^\circ}$$
The relative rate of abstraction of hydrogen by Cl is 
$$\underset{(5)}{3^\circ} \, > \, \underset{(3.8)}{2^\circ} \, > \, \underset{(1)}{1^\circ}$$
$$CH_3 - \overset{CH_3}{\overset{|}{\underset{CH_3}{\underset{|}C}}} -CH_2 - \overset{CH_3}{\overset{|}CH} - CH_3 \xrightarrow{Br_2/hv} CH_3 - \overset{CH_3}{\overset{|}{\underset{CH_3}{\underset{|}C}}} - CH_2 - CH_2 - \overset{CH_3}{\overset{|}{\underset{Br}{\underset{|}C}}} - CH_3$$
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 $$H-C\equiv C-H+HOCl\rightarrow$$product, 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.
0:0:1


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