Asubstance is either an element or a solution, compound, heterogeneous mixture, or homogenous?

For better understanding:

Chemical element is represented by a symbol.
Solution is any homogeneous mixture.
Chemical substance is represented by a formula.
 
The substances in whose formulas only appear atoms of a chemical element are called simple substances. When there are atoms of more than one chemical element, it is a compound substance or chemical compound. Mixture is a system made up of two or more pure substances, called components.
The mixtures can be classified as homogeneous and heterogeneous. The difference between them is that the homogeneous mixture is a solution that presents a single phase while the heterogeneous can present two or more phases.

Wind will blow from one direction to another.

Ch4 and ph3 are both covalent since they are composed both of non-metals.    ch4 is non- polar because of  london forces and has a geometry of tetrahedral  ph3 , on the other hand, is umbrella shaped polar and has dipole-dipole intermolecular force (imf) . since ph3 is polar, it has a stronger imf