During gas welding of copper sheets a neutral flame was used consuming $$8$$ liters of acetylene. But the weld was found to be defective. So it was re-welded using an oxidizing flame. The likely consumption of oxygen in liters will be

In welding process, penetration is increased by

In welding a mild steel sheet using an oxy-acetylene flame, the total amount of acetylene consumed was $$8.0$$ liters the oxygen consumption from the cylinder is