Azeotropes are constant boiling mixtures which distill out unchanged in their composition.
Minimum boiling azeotropes are formed by solutions showing positive deviation, e.g. cyclohexane and ethanol.

(i) CH₃CH₂CN, CH₃CH₂CONH₂
(ii) CH₃CH₂CN, CH₃CH₂CH₂NH₂

(i) Chirality: It is a geometrical property of a rigid object ( or molecules ) by which it gets such spatial arrangement of points or atoms that, the molecule becomes non-super imposable of its mirror image.
The chiral molecule of the object does not have any element of symmetry like, a mirror image, centre of inversion (i) etc.
3-bromopent-1-ene is represented as
(ii) Due to +I effect of alkyl groups the 2° carbonium ion CH₃—CH⁺ —CH₂—CH₃ derived from sec. butyl chloride is more stable than the 1° carbonium ion CH₃—CH₂—C H₂⁺ derived from n-propyl chloride. Therefore sec. butyl chloride gets hydrolyzed more easily than n-propyl chloride under SN1 conditions.
This is because; iodine is a better leaving group due to its large size. So, it will be released at a faster rate in the presence of an incoming nucleophile

The decrease in atomic and ionic size with increase in atomic number in lanthanoids is called lanthanoid contraction.
Consequences:
(i) There is close resemblance between 4d and 5d transition series.
(ii) Lanthanides have similar chemical properties due to similar ionic size.

\(=\frac{W_E}{M_E} \times \frac{1000}{\text { Volume of solution in ml }}=\frac{6}{60} \times \frac{1000}{1000}=0.1 \mathrm{M} \text {. }\)

In aqueous solution, copper (1) undergoes disproportionation reaction. 
2Cu (aq) ⟶ Ca³+Co(s)
The highest stability of Cu ion in aqueous solution is due to negative enthalpy of hydration.
Hence, Cu is not known (or unstable) in aqueous solution

\(\text {Given, } K_{f} =1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}, W_{2}=0.5 \mathrm{~g}, W_{1}=100 \mathrm{~g} \)
\(\Delta T_{f} =0.24^{\circ}\)
Observed molecular mass of KCl
\(=\frac{1000 \times K_{f} \times W_{2}}{\Delta T_{f} \times W_{1}}\)
\(=\frac{1000 \times 1.86 \times 0.5}{0.24 \times 100}=38.75\)
Normal molecular mass of  \( \mathrm{KCl}=38.75+35.5=74.25\)
\(\text {van't Hoff factor }=\frac{\text { Normal molecular mass }}{\text { Observed molecular mass }} \)
\(i=\frac{74.25}{38.75}=1.92\)
\( \underset{(1-\alpha)}{\mathrm{KCl}} \rightleftharpoons \underset{\alpha}{\mathrm{K}^{+}}+\underset{\alpha}{\mathrm{Cl}^{-}} Total \ number \ of\ particles =1-\alpha+\alpha+\alpha=1+\alpha\)
\(i=1+\alpha \quad 1.92=1+\alpha\)
\(So, \alpha=1.92-1=0.92, i.e. 92 \% \ dissociated.\)

Maximum boiling azeotropes
Maximum boiling azeotropes are those which boil at a higher temperature than the boiling point of each component in a pure state,
e.g., 68 % nitric acid and 32 % water by mass. 
Minimum boiling azeotropes
Minimum boiling azeotropes are those which boil at a lower temperature than boiling point of each component in the pure state,
​​​​​​​ e.g., 95.5 % ethyl alcohol and 4.5 % water by mass. 

Mass of CaCl₂ (W₂) =10g
Mass of water (W₁) = 200 g
Molar mass of CaCl₂ (M₂) = 111 g mol^-1
K_b=0.512 K kg mol^-1
\(m=\frac{W_2\times 1000}{M_2 \times W_1} \Rightarrow m=\frac{10}{111}\times \frac{1000}{200}\)
\(m=0.450 \ kg \ mol^{-1} , \Delta T_b = K_b\times m\)
0 = 0.512 kg mol^-1 x 0.450 m = 0.2304 K

(i)

(ii) CH₃CH₂CI + AgNO₂\(\rightarrow\)CH₃CH₂NO₂+AgCI
(iii) CH₃CH₂CH₂CH(Br)CH₃ + KOH(alc.)\(\rightarrow\)CH₃CH₂CH=CH CH₃

(i) Zinc (Z= 30, 1822822p6 3823p6 3d10 482)does not have partially filled d-subshell in its elementary state or in its commonly occurring oxidation state (Zn2+: 3dlO). Therefore, it is not regarded as a transition element.
(ii) Transition elements or the d-block elements from a large number of coordination complexes. The transition metal ions bind to a number of anions or neutral molecules in these complexes. The common examples are [Ni(NHJJ2+, [Co(NHJJ3-, [Fe(CN)J3+,
[Fe(CN)J4-, [Cu(NH3)4]2+e,etc. The high tendency of transition metal ions to form complexes is due to
(a) small size of the atoms and ions of transition metals
(b) high nuclear charge
(c) availability of vacant d-orbitals of suitable energy to accept lone pairs of electrons donated by other groups (called ligands).
(iii) Mn2+ has 3d5 electronic configuration. It is stable because of the half-filled configuration of d-subshell. Therefore, Mn has very high third ionization enthalpy for the change from d5 to d4 and it is responsible for much more positive EOvalue for Mn3+/Mn2+couple in comparison to Cr3+/Cr2+couple.

(a) (i) Chlorobenzene and Benzyl chloride Take both the compounds in a test tube. Add 1 - 2 ml of aqueous KOH to each of the test tubes. Acidify with dilute HNO₃ and add AgNO₃. Benzyl chloride gives white precipitate while chlorobenzene does not.
(ii) Chloroform and Carbon tetrachloride Chloroform on warming with alcoholic KOH and aniline will give foul smell of isocyanide; whereas, Carbon tetrachloride will not show any change.
(b) Methyl chloride hydrolysed more easily than chlorobenzene. It is due to double bond character in chlorobenzene due to resonance which is difficult to break as compared to single bond (C—Cl) in CH₃Cl.

\(NaCl\longrightarrow { Na }^{ + }+{ Cl }^{ - },i=2\\ \Delta { T }_{ f }={ iK }_{ f }m=2\times 1.86\times 0.1={ 0.372 }^{ o }C,\\ { T }_{ f }={ 0.372 }^{ o }C.\)

On increasing the temperature, volume of the solution increases. Hence Molarity decreases.

(a) \(\text { (i) } \mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}_{2}+\mathrm{HBr} \stackrel{\text { Peroxide }}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br} \frac{\mathrm{Ag} \mathrm{F}}{\text { Swartz reaction }} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{~F}\)
                 Prop-1-ene                                        1-Bromopropane                           1-Fluoropropane  
      
\(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH} \stackrel{\mathrm{PCl}_{5}}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl} \quad \stackrel{\mathrm{KCN}}{\longrightarrow} \quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CN}\)
         Ethanol                   Chloroethane                Propane nitrile
(b) Chlorobenzene is resonance hybrid of following structures:

Since, electron density is maximum at o-and p-positions due to +R effect, therefore, electrophilic substitution will take place at o and p-positions.

(i) The van't Hoff factor is a measure of the effect of a solute upon colligative properties such as osmotic pressure, relative lowering in vapour pressure, the elevation of boiling point and freezing point depression.
The van't Hoff factor is the ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass.
\(= \frac{observed \ molecular \ mass}{mormal \ molecular \ mass}\) 
(ii) The van 't Hoff factor is the ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass. if solute particles undergo association then , i<1 and if dissociation then, i > 1.
(iii) M₂ = 12.4g
M_H2O = 1.0kg
T_b = 373.0832K
T_b⁰ = 373.15K
K_b = 0.52km^₋₁
M₂ = 208.34
α = ?
ΔT_b = iK_b × m
373.0832 − 373 = \(i=\frac{208.34\times1}{0.52\times12.48\times1000}\)
​i = 2.67
BaCl₂ →Ba₂⁺ + 2Cl⁻
n = 3
\(\alpha=\frac{i-1}{n-1}=\frac{2.67-1}{3-1}\)
= 83.55%

(a) (i) \( \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+3 \mathrm{H}_{2} \mathrm{~S}(g)+8 \mathrm{H}^{+}(a q) \) \(\longrightarrow 2 \mathrm{Cr}^{3+}+3 \mathrm{~S}+7 \mathrm{H}_{2} \mathrm{O}\)
(ii) \( 2 \mathrm{Cu}^{2+}(a q)+2 \mathrm{I}^{-}(a q) \longrightarrow 2 \mathrm{Cu}^{+}(a q)+\mathrm{I}_{2}(s)\)
(b) (i) It is because V in lower oxidation the state is less stable than Cr which is less stable than Mn. That is why MnO₄ is a best oxidizing agent and VO²⁺ is least.
(ii) M n (2 5) has electronic configuration [Ar]4s23ds, electronic configuration of Mn²⁺ is [Ar]4so3ds. After losing 2 electrons, it has half filled d-orbital, which is more stable that is why Mn²⁺ has exceptionally high third ionization energy, i.e. the energy required to remove
the third electron is very high.
(iii) It is because in Cr³⁺, d3 (half filled t2g orbitals) is more stable in aqueous solution than Fe³⁺ i.e. Cr³⁺ is more stable than Fe³⁺.

C) Assertion is correct statement but reason is wrong statement.
Explanation:
Benzene and toluene do not form H-bonding with each other.

(c) (A) is correct but (R) is incorrect. Presence of - Cl in chlorobenzene activates the ring at ortho and, para-positions and therefore, nitration of chlorobenzene leads to the formation of o- and p-chloro nitro chlorobenzene. NO₂ group is a meta-directing group.

(a) In case of optically active alkyl halides, S_N1 reactions are accompanied by racemisation. The carbocation formed in the slow step being sp² -hybridised is planar (achiral). The attack of the nucleophile may be from either side resulting mixture of products. One product has same configuration, while other has opposite configuration. Thus, both (A) and (R) are correct and (R) is the correct explanation of (A).

(iii) (b)