Yeah its enough if you're not used to it maybe. Try taking 5 in the morning and 5 before your test IF you take any. I wouldn't myself as Benzos affect your co-ordination. Think of it as being a little bit drunk and stoned: Relaxed and happy but also forgetful and uncoordinated- you might ruin your chances if you're not used to it.
I was prescribed and was addicted to benzodiazepines a long while ago now and would take 100mg+ a day or the equivalent benzo- sometimes much more than this- this doesn't mean he should take 2 blues before his test.
A word of warning- If you have an addictive streak watch out as they can become habit-forming and I've done some really regrettable things I cant even remember while wasted. The withdrawal symptoms are also awful and can last for months.
Valium (Diazepam) is a benzodiazepine and is not comparable with Vicodin (Oxycodone) which is an opiate. It may, however, provide a sense of well-being or relaxation similar to the effects of other drugs.
Having a read of experiences in the Diazepam section on
Erowid is probably not a bad idea. Good luck with the test.