Nitrogen and hydrogen
N2 +3 H2 ---> 2NH3
hope that answers the question:)
8: this model is similar to a real life model because it shows what you can have in and around your house
9: the way this model can be useful is by helping show how to build your house the way you want it to be and what you would want
This feature of DNA is termed complimentary base pairing, in that the base that compliments a certain base, say A, is always paired with base T, and likewise every T has its pair partner always as A. The same holds true with C with G, and vice versa.