Most important tool a scientist can have

I dont think any tool is the most important tool a scientiest can have but if i had to pick one I would go with the scientific method.

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   

I’m really not sure what’s the answer. sorry