2.2) Two chains of DNA must run in _________ direction(s) and must be ________ if they are to bond with each other.
The answer is 5. Antiparallel; complementary.
The two strands of DNA are antiparallel i.e. the 5' → 3' direction and the two DNA chains are held together by complementary base pairing between A and T bases and between G and C bases.