I think..attempting with headings will be better.But marks solely depend upon knowledge (aya't,hadith and other references).
As for as i know..there is no single book which should cover everything.....if you are opting urdu for islamiat...islami nazrya e hayat by prof. Khursheed ahmed is the best book..have ever seen and read.

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Plan with attitude ,prepare with aptitude,participate with servitude,receive with gratitude.