Question

3. Which material is called 'black gold'? Why?

Answer 1

Answer:

Petroleum

Explanation:

petroleum is a black colored  oil when it comes out of the ground and is used for many purposes like lubricating oil, fuel,...etc. many products like petrol,  diesel , paraffin wax , are obtained by the process of fractional distillation . therefore it is of a great worth , and so it is called as black gold .