Chemistry NCERT Exemplar Solutions Class 11th Chapter Thirteen: Overview, Questions, Preparation

The relative reactivity of 1°, 2°, 3° hydrogen’s towards chlorination is 1 : 3.8 : 5. Calculate the percentages of all monochlorinated products obtained from 2-methylbutane.

Write the structures and names of products obtained in the reactions of sodium with a mixture of 1-iodo-2-methylpropane and 2-iodopropane.

Nucleophiles and electrophiles are reaction intermediates having electron rich and electron deficient centres respectively. Hence, they tend to attack electron deficient and electron rich centres respectively. Classify the following species as electrophiles and nucleophiles.

Write hydrocarbon radicals that can be formed as intermediates during monochlorination of 2-methylpropane? Which of them is more stable? Give reasons

Arrange the following in decreasing order of their boiling points.

(A) n–butane

(B) 2–methylbutane

(C) n-pentane

(D) 2,2–dimethylpropane

(i) A > B > C > D

(ii) B > C > D > A

(iii) D > C > B > A

(iv) C > B > D > A

Arrange the following hydrogen halides in order of their decreasing reactivity with propene. 

(i) HCl>HBr> HI 

(ii) HBr> HI >HCl

(iii) HI >HBr>HCl

(iv) HCl> HI >HBr

An alkyl halide C₅H₁₁Br (A) reacts with ethanolic KOH to give an alkene ‘B’, which reacts with Br₂ to give a compound ‘C’, which on dehydrobromination gives an alkyne ‘D’. On treatment with sodium metal in liquid ammonia one mole of ‘D’ gives one mole of the sodium salt of ‘D’ and half a mole of hydrogen gas. Complete hydrogenation of ‘D’ yields a straight chain alkane. Identify A,B, C and D. Give the reactions invovled.

896 mL vapour of a hydrocarbon ‘A’ having carbon 87.80% and hydrogen 12.19% weighs 3.28g at STP. Hydrogenation of ‘A’ gives 2-methylpentane. Also ‘A’ on hydration in the presence of H₂SO₄ and HgSO₄ gives a ketone ‘B’ having molecular formula C₆H₁₂O. The ketone ‘B’ gives a positive iodoform test. Find the structure of ‘A’ and give the reactions involved.

An unsaturated hydrocarbon ‘A’ adds two molecules of H₂ and on reductive ozonolysis gives butane-1,4-dial, ethanal and propanone. Give the structure of ‘A’, write its IUPAC name and explain the reactions involved.

In the presence of peroxide addition of HBr to propene takes place according to anti Markovnikov’s rule but peroxide effect is not seen in the case of HCl and HI. Explain.

Why do alkenes prefer to undergo electrophilic addition reaction while arenes prefer electrophilic substitution reactions? Explain.

Alkynes on reduction with sodium in liquid ammonia form trans alkenes. Will the butene thus formed on reduction of 2-butyne show the geometrical isomerism?

The intermediate carbocation formed in the reactions of HI, HBr and HCl with propene is the same and the bond energy of HCl, HBr and HI is 430.5 kJ mol^–1, 363.7 kJ mol^–1 and 296.8 kJ mol^–1 respectively. What will be the order of reactivity of these halogen acids?

Arrange the following set of compounds in the order of their decreasing relative reactivity with an electrophile.Give reason

Why does presence of a nitro group make the benzene ring less reactive in comparison to the unsubstituted benzene ring. Explain.

An alkane C₈H₁₈ is obtained as the only product on subjecting a primary alkyl halide to Wurtz reaction. On monobromination this alkane yields a single isomer of a tertiary bromide. Write the structure of alkane and the tertiary bromide.

Arrange the halogens F₂, Cl₂, Br₂, I₂, in order of their increasing reactivity with alkanes. 

(i) I₂< Br₂< Cl₂< F₂

(ii) Br₂< Cl₂< F₂< I₂

(iii) F₂< Cl₂< Br₂< I₂

(iv) Br₂< I₂ < Cl₂< F₂

The increasing order of reduction of alkyl halides with zinc and dilute HCl is 

(i) R–Cl< R–I < R–Br 

(ii) R–Cl< R–Br < R–I 

(iii) R–I < R–Br < R–Cl

(iv) R–Br< R–I < R–Cl

The correct IUPAC name of the following alkane is

(i) 3, 6 – Diethyl – 2 – methyl octane 

(ii) 5 – Isopropyl – 3 – ethyl octane 

(iii) 3 – Ethyl – 5 – isopropyl octane 

(iv) 3 – Isopropyl – 6 – ethyl octane

The addition of HBr to 1-butene gives a mixture of products A, B and C

The mixture consists of 

(i) A and B as major and C as minor products 

(ii) B as major, A and C as minor products 

(iii) B as minor, A and C as major products 

(iv) A and B as minor and C as major products

Arrange the following carbanions in order of their decreasing stability.

(A) H₃C - C ≡ C ^-(B) H - C ≡ C ^- (C) H₃C - CH₂

(i) A > B > C 

(ii) B > A > C 

(iii) C > B > A 

(iv) C > A > B

Arrange the following alkyl halides in decreasing order of the rate of β– elimination reaction with alcoholic KOH.

 (B) CH₃—CH₂—Br

 (C) CH₃—CH₂—CH₂—Br

(i) A > B > C 

(ii) C > B > A 

(iii) B > C > A 

(iv) A> C > B

Which of the following reactions of methane is incomplete combustion:

(i) 2CH₄ + O₂ 2CH₃OH

(ii) CH₄ + O₂ HCHO +  H₂O   

(iii) CH₄ + O₂ → C (s) +  2H₂O (l)

(iv) CH₄ + O₂ → CO₂ (g) +  2H₂O (l)

In the following questions two or more options may be correct.

(i) CH₄ + O₂ → CO₂ (g) +  2H₂O (l)

(ii) CH₄ + O₂ → C (s) +  2H₂O (l)

(iii) CH₄ + O₂   HCHO +  H₂O   

(iv) 2CH₄ + O₂2CH₃OH

Which are the correct IUPAC names of the following compound?

(i) 5– Butyl – 4– isopropyldecane

(ii) 5– Ethyl – 4– propyldecane

(iii) 5– sec-Butyl – 4– iso-propyldecane

(iv) 4–(1-methylethyl)– 5 – (1-methylpropyl)-decane

For an electrophilic substitution reaction, the presence of a halogen atom in the benzene ring _______. 

(i) Deactivates the ring by inductive effect 

(ii) Deactivates the ring by resonance

(iii) Increases the charge density at ortho and para position relative to meta position by resonance 

(iv) Directs the incoming electrophile to meta position by increasing the charge density relative to ortho and para position.

In an electrophilic substitution reaction of nitrobenzene, the presence of nitro group ________. 

(i) Deactivates the ring by inductive effect. 

(ii) Activates the ring by inductive effect. 

(iii) Decreases the charge density at ortho and para position of the ring relative to meta position by resonance. 

(iv) Increases the charge density at meta position relative to the ortho and para positions of the ring by resonance

(i) CH₃—O—CH₂^⊕ is more stable than CH₃—CH₂^⊕

(ii) (CH₃)₂CH^⊕ is less stable than CH₃—CH₂—CH₂^⊕

(iii) CH₂=CH—CH₂^⊕ is more stable than CH₃—CH₂—CH₂^⊕

(iv) CH₂=CH^⊕is more stable than CH₃—CH₂^⊕

Four structures are given in options (i) to (iv). Examine them and select the aromatic structures.

The molecules having dipole moment are __________. 

(i) 2,2-Dimethylpropane 

(ii) Trans-Pent-2-ene 

(iii) Cis-Hex-3-ene 

(iv) 2, 2, 3, 3 - Tetramethylbutane.

Match the reagent from Column I which on reaction with 

CH₃ – CH=CH₂ gives some product given in Column II as per the codes given below:

It is cyclic and has conjugated 8π-electron system but it is not an aromatic compound.

Reason (R) : (4n + 2) π electrons rule does not hold good and ring is not planar.

(i) Both A and R are correct and R is the correct explanation of A.

(ii) Both A and R are correct but R is not the correct explanation of A.

(iii) Both A and R are not correct.

(iv) A is not correct but R is correct.

Assertion (A): Toluene on Friedal Crafts methylation gives o– and p–xylene. 

Reason (R): CH₃-group bonded to benzene ring increases electron density at o– and p– position. 

(i) Both A and R are correct and R is the correct explanation of A. 

(ii) Both A and R are correct but R is not the correct explanation of A. 

(iii) Both A and R are not correct. 

(iv) A is not correct but R is correct.

Assertion (A): Nitration of benzene with nitric acid requires the use of concentrated sulphuric acid. 

Reason (R): The mixture of concentrated sulphuric acid and concentrated nitric acid produces the electrophile, NO₂ ⁺. 

(i) Both A and R are correct and R is the correct explanation of A. 

(ii) Both A and R are correct but R is not the correct explanation of A. 

(iii) Both A and R are not correct. 

(iv) A is not correct but R is correct.

Assertion (A): Among isomeric pentanes, 2, 2-dimethylpentane has highest boiling point. 

Reason (R): Branching does not affect the boiling point. 

(i) Both A and R are correct and R is the correct explanation of A. 

(ii) Both A and R are correct but R is not the correct explanation of A. 

(iii) Both A and R are not correct. 

(iv) A is not correct but R is correct.

1.34% solution of KNO? is isotonic with 4.77% solution of glucose. Find the percent of dissociation of KNO?. (Given : Atomic mass K = 39.1 amu, N = 14 amu and O = 16 amu)

A weakly alkaline solution of permanganate is electrolysed for 50 minutes using 2A current. The amount of oxide of manganese obtained. (Given : Atomic mass Mn = 55 amu and O = 16 amu)

The density of a solution prepared by dissolving 1 gram molecule of sucrose in 1000 gram of water is 1.15 gm/ml. The molarity of the solution is ____.

How many peroxide linkages are present in a compound of chromium with oxygen which is blue in colour and soluble in amyl alcohol, produced by treating K?CrO? with acidified H?O??

How many of these compounds will undergo disproportionation on hydrolysis? CO?, NO?, Cl?, F?, ClO?, Cl?O?, N?O?, SO?, P?O??

Identify the numbers of amphiprotic species in the following list?
H?O?, HPO?²?, HCO??, H?O, HPO?²?, H?PO?, H?PO??, H?PO?, PO?³?, NH??

Number of geometrical isomers of a complex ion [Pt(PPh?)?(Py)?Cl?]²? are x, if 1 mole of ethylenediamine replaces two weakest ligands then new complex formed has ‘y’ number of geometrical isomers. Find the values of x/y.

For the reaction aA + bB->cC + dD, the plot of log K vs $\frac{1}{T}$  is given below:

This temperature at which the rate constant of the reaction is 10^-4 s^-1 is----------K.

(Rounded – off to the nearest integer)

[Given : The rate constant of the reaction is 10^-5 s^-1 at 500 K]

In basic medium $Cr{O}_4^{2-}$  oxidises $S_2{O}_3^{2-}$ to form  $S{O}_4^{2-}$ and itself changes into Cr(OH)₄^-. The volume of 0.154M  $Cr{O}_4^{2-}$ required to react with 40mL of 0.25 M $S_2{O}_3^{2-}is$ -------------- mL.

(Rounded – off to the nearest integer)

0.4g mixture of NaOH, Na₂CO₃ and some inert impurities was first titrated with $\frac{N}{10}HCl$  using phenolphthalein as an indicator, 17.5mL of HCl was required at the end point . After this methyl orange was added and titrated. 1.5mL of same HCl was required for the next end point. The weight percentage of Na₂CO₃ in the mixture is----------. (Rounded – off to the nearest integer)

The reaction of cyanamide, NH₂CN_(s) with oxygen was run in a bomb calorimeter and  $\Delta U$ was found to be -742.24 kJ mol^-1. The magnitude of $\Delta H_{298}$  for the reaction

------------- kJ. (Rounded off to the nearest integer)

[Assume ideal gases and R = 8.314 J mol^-1 K^-1]

1 molal aqueous solution of an electrolyte A₂B₃ is 60% ionized. The boiling point of the solution at 1 atm is----------- K. (Rounded – off to the nearest integer)

[Given K_b for (H₂O) = 0.52 K kg mol^-1]

A car tyre is filled with nitrogen gas at 35 psi at 27°C. It will burst if pressure exceeds 40 psi. The temperature in °C at which the car tyre will burst is--------------. (Rounded – off to the nearest integer)

The ionization enthalpy of Na⁺ formation from Na_(g) is 495.8 kJ mol^-1, while the electron gain enthalpy of Br is - 325.0 kJ mol^-1. Given the lattice enthalpy of NaBr is - 728.4 kJ mol^-1. The energy for the formation of NaBr ionic solid is (-) -------------- × 10^-1kJ mol^-1.

Using the provided information in the following paper chromatogram: Fig : Paper chromatography for compounds A and B. The calculated R_f value of A------------× 10^-1

Consider the following chemical reaction.

$HC\equiv CH\underset{2)CO,HCl,AlC{l}_3}{\overset{1)RedhotFetube,873K}{\to }}Product$            

The number of sp² hybridized carbon atoms (s) present in the product is--------------.