Question

The chain silicates having the general formula ${(Si{O}_3{)}_n}^{-2n}$ contain $100$ basic units. What will be the formula of silicates?
(A) $S{i}_{100}{O_{300}}^{-200}$
(B) $S{i}_{100}{O_{300}}^{-201}$
(C) $S{i}_{100}{O_{301}}^{-202}$
(D) $S{i}_{100}{O_{302}}^{-200}$

Answer 1

Hint : Here, the general formula for chain silicates is given ${(Si{O}_3{)}_n}^{-2n}$ . So, basically silicates are the anions which consist of silicon and oxygen. In silicates, there is only one type of bond present which is between silicon and oxygen $(Si-O)$ .

Complete Step By Step Answer:
The silicate mineral is composed of a silicate group. Silicate is an anion consisting of silicon and oxygen and only $Si-O$ bonds are present. Silicates has a general formula $(Si{O_{4-x}}^{(4-2x)-}{)}_n$ where, $0⩽x⩽2$ .The hybridization of silicon in silicates is $s{p}^3$ . $Si{O_4}^{-4}$ forms a tetrahedral i.e. the $Si$ is present at the center of the tetrahedral with oxygen which occupies the four corners of the tetrahedral. Silica is a giant crystalline polymer with a tetrahedral monomer $Si{O_4}^{-4}$ . Here, the oxygen atom is surrounded by two silicon atoms $(Si-O-Si)$ . The hybridization of silicon in silica is $s{p}^3$ .
There are many types of silica such as pyrosilicates $S{i}_2{O_7}^{6-}$ , cyclic or ring silicates $[Si{O_3}^{2-}{]}_n$ , orthosilicates $Si{O_4}^{4-}$ , chain silicates $[S{i}_2{O_5}^{2-}{]}_n$ , sheet silicates $[S{i}_2{O_5}^{2-}{]}_n$ and $3D$ silicates.
In this question, the general formula for chain silicates is given ${(Si{O}_3{)}_n}^{-2n}$ and the chain silicates contain $100$ basic units. We have to derive the formula of silicates.
So, $n=100$
Put the value of n in the general formula ${(Si{}_n{O}_3{)}_n}^{-2n}$
We get, ${(S{i}_{100}{O}_3{)}_{100}}^{-2(100)}$
 $={(S{i}_{100}{O}_3{)}_{100}}^{-200}$
 $=S{i}_{100}{O}_3{}_{00}^{-200}$
Hence, the correct answer is option (A).

Note :
The term ‘silicates’ is used to mean ionic solids with silicates ions, silicates minerals. They are the rock forming minerals. Silica rock is a type of sedimentary rocks Silica sand or quartz sand is silica ore. Silicates are used to make cuvettes, prism eyeglasses and abrasive material. Silica is mostly present in crystalline form like quartz and amorphous form like cristobalite.