(A)Each silicon atom is surrounded by four oxygen atoms and each oxygen atom is bonded to two silicon atoms✓ Correct
(B)Each silicon atom is surrounded by two oxygen atoms and each oxygen atom is bonded to two silicon atoms
(C)Silicon atoms is bonded to two oxygen atoms
(D)there are double bonds between silicon and oxygen atoms
Answer: (A)
Solution
Silica is not made of discrete SiOX2 molecules but of an endless three-dimensional network. Every silicon sits at the centre of a tetrahedron of four oxygen atoms, and every oxygen bridges between two such silicons in Si−O−Si links that repeat throughout the solid. That sharing, four oxygens round each silicon and each oxygen shared by two silicons, is what gives the overall SiOX2 ratio and the rigid, high-melting structure.
JEE Main · 2005 · 08 May 2005 · Offline · Single correct option
