Question

When an excess of silica is heated with coke in an electric furnace in the absence of air, ________ coloured silicon is obtained.

• A. pale yellow
• B. dark brown
• C. dark grey
• D. crimson red

Answer 1

The correct option is C dark grey

Crystalline silicon is obtained by reducing silica with coke. When excess of silica is heated with coke in the electric furnace in the absence of air dark grey coloured silicon is obtained in its crystalline form.

$Si{O}_2+2C⟶Si+2CO\uparrow$