Include in your answer:
-foam is a colloid.
-colloids include gas dispersed in a liquid.
-colloids include gas dispersed in a solid.
The chemical formula of nitrogen dioxide is NO2. It is a brown coloured gas.
Organic elements, depends on the context of the question but I suspect that is the answer. The organic elements are H,O,C,N,P,S
It gives the positive ion and negative ion and the charges