Q. With reference to 'fly ash' produced by the power plants using coal as fuel. Which among the given statements is/are right? 
1. Fly ash can be used in the production of bricks for building construction. 
2. Fly ash can be used as a replacement for some of the Portland cement contents of concrete.
3. Fly ash is made up of silicon dioxide and calcium oxide only, and does not contain any toxic elements. 
Select the right answer using the code given below