Question

Pyroxenes are class of silicate minerals, which exhibit a polymeric chain structure, as shown below



Its simplest repeating unit is

• A. $\left[\right. S i O_{4} \left]\right. ^{4 -}$
• B. $\left[\right. S i O_{3} \left]\right. ^{2 -}$
• C. $\left[\right. S i_{2} O_{7} \left]\right. ^{6 -}$
• D. $\left[\right. S i_{4} O_{11} \left]\right. ^{6 -}$

Answer 1

Answer: (B)

In pyroxenes, there is a total of 3 oxygen atoms per silicon atom, so the simplest repeating unit is $\left[\text{SiO}_{\text{3}}\right]^{\text{2} -}$ or $\left[\text{SiO}_{\text{3}}\right]_{\text{n}}^{\text{2n} -}$