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GATE 2023 CY – Question 42

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). · 2 marks · Multiple choice

The numbers of shared corners per constituent $SiO_4$ unit in orthosilicate, pyrosilicate, cyclic silicate, and sheet silicate, respectively, are ______.

  1. 0, 1, 2 and 3
  2. 2, 3, 0 and 1
  3. 0, 3, 1 and 2
  4. 1, 2, 3 and 0

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Correct answer: (A) 0, 1, 2 and 3

Explanation

Orthosilicate tetrahedra are isolated, sharing zero corners. Pyrosilicate dimers share one; ring silicates link each tetrahedron to two neighbours. Sheets extend in two dimensions with three shared corners per unit. Sequence **0,1,2,3, A** follows directly from their connectivity.