An unknown or changeable quantity is called a(

An unknown and changeable quantity is known as an variable.

Explanation:

There are two types of quantities:

Constant quantities:

Quantities which can not be changed by changing physical parameters and their value is normally known.

Variable quantities:

These quantities can be changed by changing the physical parameters or conditions. Due to which they are unknown for particular conditions and have to be measured.

The answer should be c.

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