ANS:B - sand & coke

A mixture of phosphate rock sand & coke is heated in an electric furnace to produce phosphorous. Explanation:

1. Phosphorous Production: Phosphorous (P) is typically produced by heating phosphate rock in an electric furnace in the presence of a reducing agent such as coke. This process is known as the electric furnace process.
2. Composition of Mixture: In the electric furnace process, the mixture typically consists of phosphate rock and a reducing agent, which is usually coke. However, the mixture may also contain other materials depending on the specific process requirements.
3. Role of Sand: Sand (silicon dioxide, SiO2) is often added to the mixture along with coke. Sand helps to provide a suitable environment for the reduction reaction by acting as a flux and promoting the formation of a slag layer. The slag helps to remove impurities from the phosphate rock during the heating process.
4. Role of Coke: Coke (carbon) serves as the reducing agent in the process. It reacts with the phosphate rock at high temperatures, causing the reduction of phosphorus pentoxide (P2O5) in the rock to elemental phosphorous (P).
5. Heating Process: The mixture of phosphate rock, sand, and coke is heated in an electric furnace to high temperatures, typically above 1400°C. At these temperatures, the reduction reaction takes place, resulting in the production of phosphorous vapor, which is then collected and condensed to obtain the final product.