For sure you can take up the board exams again but not from the same board 

To appear from the same board you need wait till the next session.

But you have an alternative to appear for the exams again from any other recognized board, Like NIOS, NWAC or any other valid state board which conducts exams in the month of June.

no only one subject is valid in 2018

I give 12 STDs exam in science stream but i fail in 2 subjects so can i give exam in July

I don't know about that please help me

Hello Yash,

If you will fail in 2 subject in your final 12th class exam, according to GSHSEB you can still appear in supplementary exam which are held in the month of july.   So when your results come out and hopefully you pass in all subjects but if you don't then you should go to your school administration office and ask for the procedure to apper for supplementary exam and where you can get its form ( from school or any specific govt. bank) and then fill it and submit it with every document required within the due date.

All the best for your results and further exams.

Hi Yash,

If in case you fail in gujarat board for 2 subjects, you can appear for the re examination which will be held in july.