i would like to known the date of issuing the application form for cbse class 12 improvement in chennai region . i also like to know whether the improvement certificate is valid for applying for any course.also whether cbse is taking the better mark out of the two exams for eg if i have got 80 marks in first cbse conducted exam and 72 mark in the improvement exam which mark cbse will be taking 80 or 72. also if i got 84 for chemistry and 87 for biology and 80 for physics in the first exam but after improvement if i got only 78 for chemistry 79 for biology and 95 for physics how the marks will come in the final certificate whether it come as chem 78 bio 79 physics 95 or the good marks will be coming like chem 84 bio 87 physics 95 ?????