Question

the theory suggests that protoplanets began to form around the protosun from many collisions and combinations of gas and matter, called .

Explanation:

The first blank refers to the "nebular" theory (the nebular hypothesis) which explains the formation of the solar system, including protoplanets forming around the protosun. The second blank is "planetesimals" as planetesimals are the small bodies (from collisions and combinations of gas and matter) that accrete to form protoplanets.

Answer:

First blank: nebular; Second blank: planetesimals