Consider the equation CO2 ---> C+ O2. What type of reaction is this?

synthesis
decomposition
single displacement
double displacement

Maybe you should get some from your teacher and learn more so you can get your grades up and maybe study a bit more

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