Replication fork is a point on the parental DNA where the DNA is being unwound and separated; and the separated strands are being replicated. Synthesis of a new DNA strand occurs in a 5' -> 3' direction, as the DNA strand serving as the template is read from its 3' -> 5' direction. During replication, two strands of DNA are synthesized: The leading strand is synthesized continuously in the same direction as the replication fork movement while the lagging strand is synthesized discontinuously in the direction opposite to the direction of fork movement, that is, towards the replication fork. The lagging strand is synthesized in short fragments known as Okazaki fragments.
When we look at reproduction too they are similar. They both produce gametes that fuse to form a zygote. They both have DNA that replicates to produce copies of itself.
H2 is molecular hydrogen.it is a molecule of hydrogen that consists of two hydrogen atoms bonded together by one single bond. 2H denotes two moles of elemental hydrogen.it should be noted that elemental hydrogen is not bonded to anything.