Alength of 16.45 m in centimeters.
conv. factor set-up

There are 100cm in a metre.

16.45=16+0.45.

Therefore 16.45m=1600cm+45cm=1645cm.

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