are the time is enough ?
Yep. More than enough.
solve all questions in their order
Not necessary to solve it in order. You can take it in any order you want
drag and drop questions , can we change the answer after we choose in the drop boxes ?
You can. But if you decide to do so you will lose the previous answer
will this is enough for the exam perpration ?
That depends entirely on what you know after the preparation. Your knowledge level will decide the pass / fail result