What kind of intermolecular forces act between a hydrogen cyanide molecule and a potassium cation? If there is more than one type of intermolecular force that acts, be sure to list them all, with a comma between the name of each force.
(dipole, hydrogen-bonding, dispersion, ion-dipole)

ion-dipole

Explanation:

Let us remember that the potassium cation is an ion, a positive ion to be precise.

There is a dipole existing in the hydrogen cyanide molecule. The positive end of the dipole is on hydrogen while the negative end of the dipole is on the cyanide moiety.

The only possible interaction between the potassium cation and the hydrogen cyanide is an ion dipole interaction. The cation interacts with the cyanide moiety having a partial negative charge in the molecule.

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).

it is b that is the answer.