Hi Geethamurali, 

Congratulations for getting  a good score in your +2 . 

Sastra university demands for a minimum  +2 percentage of 98% to give a seat. Though you have a pretty good percentage  it will not be enough for you to get a seat in Australia university .

Apart from Sastra, there are also many other good engineering  colleges that don't demand such high percentage . May be you can give them a try to those colleges also. 

Hope the information was helpful 

All the very best