Purines possess nitrogen at
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(1) 5 and 3
(2) 6 and 2
(3) (−3) and (+5)
(4) 8 and (−12)
(5) (−7) and 5
(6) 10 and (−14)
(7) (−5) and (−2)
(8) (+6) and (−9)
(9) (−4) and (−1)
(10) 1 and (−5)