With reference to furnace oil, consider the following statements:
1. It is a product of oil refineries.
2. Some industries use it to generate power.
3. Its use causes sulphur emissions into environment.
Which of the statements given above are correct?

The correct option is 1, 2 and 3.

Let us analyze each statement regarding furnace oil step-by-step:

1. It is a product of oil refineries:
Furnace oil (also known as fuel oil or heavy oil) is a dark, viscous residual product obtained during the fractional distillation of crude oil in petroleum refineries. Therefore, Statement 1 is correct.

2. Some industries use it to generate power:
Furnace oil is widely used as a fuel in various industrial boilers, thermal power plants, cement factories, and electricity generators (diesel generator sets) to produce electricity and heat energy. Therefore, Statement 2 is correct.

3. Its use causes sulphur emissions into environment:
Crude oil naturally contains sulfur compounds. Since furnace oil is a heavy residual fraction, it retains a high concentration of sulfur. When burned for power or heating, it releases sulfur dioxide (SO₂) into the atmosphere, contributing to air pollution and acid rain. Therefore, Statement 3 is correct.

Since all three statements (1, 2, and 3) are correct, the correct choice is 1, 2 and 3.