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GATE 2024 CY – Question 13

Inorganic Chemistry · Main Group Elements: Shapes and structures of molecules using VSEPR postulates, Hydrides, halides, oxides, oxoacids, nitrides, sulfides - shapes and reactivity. Structure and bonding of boranes, carboranes, silicones, silicates, boron nitride, borazine and phosphazenes: electron counting in polyhedral boranes, isolobal analogy. Allotropes of carbon, phosphorus and sulfur. Industrial synthesis of compounds of main group elements such as NH3, H2SO4 and HNO3. Chemistry of noble gases and interhalogen compounds. Acid-base concepts and principles (Lewis, Brønsted, HSAB and acid-base catalysis). · 1 mark · Multiple choice

The reaction of $\mathrm{XeF_2}$ with $\mathrm{HN(SO_2F)_2}$ at 273 K in $\mathrm{CF_2Cl_2}$ solvent yields

  1. $\mathrm{XeF_4+SO_2+NH_3}$
  2. $\mathrm{Xe+SO_2+N_2+HF}$
  3. $\mathrm{SOF_2+XeO_2+NH_3}$
  4. $\mathrm{FXeN(SO_2F)_2+HF}$

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Correct answer: (D) $\mathrm{FXeN(SO_2F)_2+HF}$

Explanation

$\text{XeF}_2$ is a fluorinating agent. $\text{HN(SO}_2\text{F)}_2$ has an acidic N–H bond (the nitrogen carries two strongly electron-withdrawing $\text{SO}_2\text{F}$ groups).

**Reaction:** the acidic hydrogen combines with a fluoride from xenon, and the amide nitrogen takes the place of the fluorine on xenon:
$$\text{XeF}_2+\text{HN(SO}_2\text{F)}_2\longrightarrow\text{FXeN(SO}_2\text{F)}_2+\text{HF}.$$

The product contains a rare xenon-nitrogen bond (option D). The other options involve oxidation or decomposition products that do not follow from this simple acid-base type substitution.