If a reaction system has come to equilibrium, the concentration of products can be increased
a.
only if it is not reversible.
c.
by applying le châtelier’s principle.
b.
only if the temperature is low enough.
d.
under no circumstances.

If a reaction system has come to equilibrium, the concentration of products can be increased by applying Le Châtelier’s principle. The answer is letter C. The statements "only if it is not reversible",  "only if the temperature is low enough" and "under no circumstances" do not answer the question above.

Answer) by studying proton collisions hope this : )

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