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Question #44473

Difficulty: 8/10 | 🟢 Free

The Question

An unknown alkene $\textbf{X}$ undergoes oxidative ozonolysis ( $\ce{O3}$ at $298\text{ K}$ followed by $\ce{H2O2}$ ) to yield a single organic product $\textbf{Y}$ . When $2.44\text{ g}$ of $\textbf{Y}$ is dissolved in $50\text{ g}$ of benzene (a non-polar solvent), the freezing point of the solution is depressed by $1.024\text{ K}$ . Assuming $\textbf{Y}$ undergoes complete intermolecular hydrogen bonding to form dimers in benzene ( $K_f = 5.12\text{ K kg mol}^{-1}$ ), identify the structure of alkene $\textbf{X}$ .

Options

A.
\ce{1,2-diphenylethene}
B.
\ce{Cyclotridecene}
C.
\ce{1,4-diphenylbut-2-ene}
D.
\ce{Cyclododecene}

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Numerical_Precision

Improve calculation stamina and avoid rounding errors in high-stakes competitive examinations.

Concepts Behind This Question

Ozonolysis Fragmentation Patterns|Molecular Mass Abnormalities|Colligative Property Definition

Why This Question Is Tricky

Common Mistakes

This problem tests the intersection of organic synthesis (oxidative ozonolysis) and solution thermodynamics (colligative properties).

The 'Hidden Variable' is the dimerization of carboxylic acids in non-polar solvents via intermolecular hydrogen bonding, which halves the Van't Hoff factor ( $i = 0.5$ ).

Students who fail to account for this physical chemistry exception will calculate a molar mass of $244 \text{ g mol}^{-1}$ .

This perfectly matches the molar mass of Tridecanedioic acid ( $\ce{C13H24O4}$ ), leading them to incorrectly deduce that the original alkene was the cyclic distractor, Cyclotridecene.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Hydrocarbons - Class 11 Part 2
Concept	Ozonolysis Fragmentation Patterns
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free