Question

In roasting we need
OSufficient supply of oxygen
OLimited supply of oxygen
OAbsence of oxygen​

Answer 1

absence of oxygen I think so

Answer 2

Answer:

so both 2nd and 3rd option are correct

Explanation:

In roasting, an ore is heated in the presence of excess of air/oxygen while in calcination the ore is heated in the absence/limited supply of oxygen

hope it will help you