CBSE 12th

Diploma courses:
In case, you are a class 12th Science failed student, you may use your 10th standard marks and certificate and get yourself enrolled in Diploma courses. The various Diploma courses are:
Mechanical Engineering
Electrical Engineering
Civil Engineering
Computer Engineering
These are some of the many Diploma courses that you can do. These courses can be done directly after 10th standard, depending on your marks. And since you failed in 12th class, you may submit your 10th standards mark sheet and certificate to get into this course.
Some Relatively New Diploma Courses:
The above-mentioned courses are the traditional ones, for which a class 12th failed student is eligible. But here, I'll list some courses that are relatively new and have a good job and career opportunities. Let's take a look at these new Diploma courses:
Diploma in Marine field
There are different Diploma courses within this field like Diploma in marine engineering (based on 10th standard marks), Diploma in marine technology, other Diploma courses like welder, wireman, sailor, etc. These courses have an eligibility criteria of 10th pass. So, 12th failed students may easily apply for these courses and get accepted.
The career opportunities that these courses offer are unparalleled. The salary will be good and the career, adventurous.
But before you join any institute offering these courses, make sure that you do a good background check of it. Check whether the institute has been approved by the Government. Also check factors like- the quality of the faculty, the infrastructure and the facilities provided, whether they are following a recognised curriculum and syllabus, etc. Join only after examining these things.
Diploma in various computer courses:
A very good option indeed. There are loads of computer courses to choose from- programming, graphics design, web designing, app development, ethical hacking, digital marketing, etc. There are many institutes that offer Diploma courses on these subjects. Usually, these courses are of 6 months to 1 year long. In the end, on the completion of the course, students are given a certificate. Good institutes also provide placement in good companies. The advantage of these courses is that you may start your own business based on the skills you acquire! It is all about skills and making use of them.