Negative Deviation from Raoult's Law Maximum Boiling Azeotrope$$\text{Negative Deviation from Raoult's Law} \implies \text{Maximum Boiling Azeotrope} $$Positive Deviation from Raoult's Law Minimum Boiling Azeotrope$$\text{Positive Deviation from Raoult's Law} \implies \text{Minimum Boiling Azeotrope} $$Ideal Solution Δ Vmix = 0$$\text{Ideal Solution} \implies \Delta V{\text{mix}} = 0 $$
Core Logic
Evaluating molecular interaction behaviors:
- (A) Chloroform and Acetone: Form intermolecular hydrogen bonds, showing negative deviation from Raoult's law, which forms a maximum boiling azeotrope arrow$\rightarrow$ (III)
- (B) Ethanol and Water: Exhibit hydrogen bond disruptions, leading to positive deviation, forming a minimum boiling azeotrope arrow$\rightarrow$ (I)
- (C) Benzene and Toluene: Highly structurally similar, forming a near-perfect ideal solution where Δ Vmix = 0$\Delta V{\text{mix}} = 0$arrow$\rightarrow$ (IV)
- (D) Acetic acid in benzene: Acetic acid undergoes intermolecular hydrogen bonding inside the non-polar solvent, causing it to dimerize arrow$\rightarrow$ (II)
Step 1: Alignment Selection
Combining the pairs gives: (A)-(III), (B)-(I), (C)-(IV), (D)-(II).
Pattern Recognition
Liquid properties shortcut: Acetic acid in benzene is a classic textbook example of dimerization (i=0.5$i=0.5$). Benzene-toluene is the most famous ideal solution pair. Recognizing either instantly shortcuts the options list to the correct key.
Keywords:#maximum boiling azeotrope example#JEE Main 2025 Evening Q38#acetic acid dimerization benzene#ideal solutions delta V mix
More Solutions Previous-Year Questions
Q59jee_main_2026_21_jan_morningElevation of Boiling Point
Elements P and Q form two types of non-volatile, non-ionizable compounds PQ and PQ₂$PQ_{2}$. When 1 g of PQ is dissolved in 50 g of solvent ‘A’. Δ Tb$\Delta T_{b}$ was 1.176 K while when 1 g of PQ₂$PQ_{2}$ is dissolved in 50 g of solvent ‘A’, Δ Tb$\Delta T_{b}$ was 0.689 K. (Kb$K_{b}$ of ‘A’ = 5 K kg mol⁻¹$5\text{ K kg mol}^{-1}$). The molar masses of elements P and Q (in g mol⁻¹$\text{g mol}^{-1}$) respectively, are :
A.70, 110$70, 110$
B.65, 145$65, 145$
C.60, 25$60, 25$
D.25, 60$25, 60$
Solution
Related Formula
Δ Tb = Kb × m$$\Delta T_b = K_b \times m$$m = Weight of solute (g)Molar mass of solute × 1000Weight of solvent (g)$$m = \frac{\text{Weight of solute (g)}}{\text{Molar mass of solute}} \times \frac{1000}{\text{Weight of solvent (g)}}$$
Q72jee_main_2026_21_jan_eveningOsmotic Pressure and Isotonic Solutions
The osmotic pressure of a living cell is 12 atm at 300 K. The strength of sodium chloride solution that is isotonic with the living cell at this temperature is ____ g L⁻¹$\_\_\_\_ \text{ g L}^{-1}$. (Nearest integer)
Given: R = 0.08 L atm K⁻¹ mol⁻¹$R = 0.08 \text{ L atm K}^{-1} \text{ mol}^{-1}$
Assume complete dissociation of NaCl$\text{NaCl}$
(Given: Molar mass of Na and Cl are 23 and 35.5 g mol⁻¹$35.5 \text{ g mol}^{-1}$ respectively.)
Numerical Answer.Answer: 15 to 15
Solution
Related Formula
π = i C R T$\pi = i C R T$
Core Logic
Given:
π = 12 atm$\pi = 12 \text{ atm}$
T = 300 K$T = 300 \text{ K}$
i = 2$i = 2$ (for complete dissociation of NaCl$\text{NaCl}$)
R = 0.08 L atm K⁻¹ mol⁻¹$R = 0.08 \text{ L atm K}^{-1} \text{ mol}^{-1}$
12 = 2 × C × 0.08 × 300 12 = 48C C = 0.25 mol/L$$12 = 2 \times C \times 0.08 \times 300 \implies 12 = 48C \implies C = 0.25 \text{ mol/L}$$
Sees: osmotic pressure calculation for isotonic solutions with electrolyte dissociation.
Trap: Forgetting Van 't Hoff factor i = 2$i = 2$ for NaCl$\text{NaCl}$.
Chapter Mix
Class 12 Chemistry: Solutions
Q73jee_main_2026_21_jan_eveningElevation in Boiling Point and Vapour Pressure Lowering
A substance 'X' (1.5 g) dissolved in 150 g of a solvent 'Y' (molar mass = 300 g mol⁻¹$= 300 \text{ g mol}^{-1}$) led to an elevation of the boiling point by 0.5 K. The relative lowering in the vapour pressure of the solvent 'Y' is ____ × 10⁻²$\_\_\_\_ \times 10^{-2}$. (Nearest integer)
[Given: Kb$K_b$ of the solvent = 5.0 K kg mol⁻¹$= 5.0 \text{ K kg mol}^{-1}$]
Assume the solution to be dilute and no association or dissociation of X takes place in solution.
Sees: boiling point elevation combined with relative lowering of vapour pressure calculation.
Trap: Confusing solvent mass with solution mass when calculating mole fraction.
Chapter Mix
Class 12 Chemistry: Solutions
Q57jee_main_2026_22_january_morningHenrys Law
Consider a solution of CO₂(g)$CO_{2}(g)$ dissolved in water in a closed container.
Which one of the following plots correctly represents variation of log (partial pressure of CO₂$CO_{2}$ in vapour phase above water) [y-axis] with log (mole fraction of CO₂$CO_{2}$ in water) [x-axis] at 25°C$25^{\circ}C$?
This equation represents a straight line of the form y = mx + c$y = mx + c$, where:
y = P(g)$y = \log P(g)$x = X(g)$x = \log X(g)$
Slope (m$m$) = +1
y-intercept (c$c$) = KH$\log K_{H}$ (which is positive).
The plot of P$\log P$ versus X$\log X$ is a straight line with a positive slope and a positive intercept on the y-axis.
Step 1: Conclusion
Graph 3 corresponds to a straight line with a positive slope and a positive y-intercept.
Pattern Recognition
When variables are multiplied (P = KH X$P = K_{H} X$), their log plot is always a straight line with a slope of +1 and an intercept equal to the log of the constant.
Chapter Mix
Class 12 Chemistry: Solutions
Q70jee_main_2026_22_january_morningHenrys Law
Given below are two statements:
Statement I: The Henry's law constant KH$K_{H}$ is constant with respect to variations in solution's concentration over the range for which the solutions is ideally dilute.
Statement II: KH$K_{H}$ does not differ for the same solute in different solvents.
In the light of the above statements, choose the correct answer from the options.
A.Statement I is false but Statement II is true.$\text{Statement I is false but Statement II is true.}$
B.Statement I is true but Statement II is false.$\text{Statement I is true but Statement II is false.}$
C.Both Statement I and Statement II are true.$\text{Both Statement I and Statement II are true.}$
D.Both Statement I and Statement II are false.$\text{Both Statement I and Statement II are false.}$
Solution
Core Logic
Statement I: KH$K_H$ is independent of concentration as long as the solution behaves ideally (is very dilute). This matches the physical definition of Henry's Law constant. (True)
Statement II: Henry's Law constant (KH$K_H$) depends on the nature of the gas, the nature of the solvent, and the temperature. Therefore, it absolutely differs for the same gas dissolved in different solvents. (False)
Step 1: Final Conclusion
Statement I is true but Statement II is false.
Pattern Recognition
The constants for solubility laws (like KH$K_H$) are fundamentally tied to the intermolecular interactions between the specific solute and the specific solvent.
Chapter Mix
Class 12 Chemistry: Solutions
More Solutions Questions — jee_main_2025_07_april_evening
Practice past-year questions one chapter at a time. Pick an exam → subject → chapter and get every PYQ for that topic — pulled together from all past papers — with the chapter's key formulas alongside.