i wanted to know if a blended biodiesel can be used for a science fair projects is it possible .

You posted this question yesterday. Did you read the responses to that thread?

As I understand it,

Science Fairs involve a little research
Some writeup.
And, running an experiment.

You can certainly do a number of things with blending.

For example...

Take a can of shortening or lard.
Heat it up and make biodiesel.

Then try blending it with gasoline or kerosene.

You could even try different mixing methods... or just compare "well mixed" and "poorly mixed" fuels. A refrigerator or freezer could help with demonstrating the effects of mixing.

It may be hard to bring your refrigerator to the science fair, although small camping refrigerators are cheap enough. Or, by choosing a "SATURATED" oil to start with, you might be able to simulate the effects of cold temperatures at higher temperatures.

Recently there were some chains about using biodiesel in lanterns, and I believe the best results were blending biodiesel with a light fuel like white gas/camping gas. Look up the chains.

http://biodiesel.infopop.cc/eve/forums/a/tpc/f/71960555...781085572#5781085572

You can also blend regular vegetable oil with various lighter fuels.

And, who knows, maybe playing with saturated oils as mentioned above (shortening and lard) is a bad idea. But, you will still learn something, and can compare different mixes & etc.

Have Fun.