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GATE 2022 CY – Question 28

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 select

The CORRECT statement(s) about thallium halides is(are)

  1. TlF is highly soluble in water whereas other Tl-halides are sparingly soluble
  2. TlF adopts a distorted NaCl structure
  3. TlI3 is isomorphic with CsI3 and the oxidation state of Tl is +3
  4. Both TlBr and TlCl have CsCl structure

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Correct answer: (A) TlF is highly soluble in water whereas other Tl-halides are sparingly soluble; (B) TlF adopts a distorted NaCl structure; (D) Both TlBr and TlCl have CsCl structure

Explanation

TlF is unusually water-soluble and has a distorted NaCl lattice, A/B true. TlCl and TlBr have CsCl-type structures, D true. TlI3 is a Tl(I) triiodide salt containing I3−, so its thallium oxidation state is+1 rather than+3.

Thus **A, B, D**.