Be sure to answer all parts. select the type(s) of intermolecular forces that exists between molecules (or basic units) in each of the following species:
(a) brf
(b) ch4
(c) so2

Explanation:

Dipole-dipole forces are defined as the forces which are present within the positive end of one polar molecule and negative end of another polar molecule.

Dispersion forces are defined as the forces which exist between the nucleus and electrons of atoms of a molecule. These forces form a temporary charge on the combining atoms.

When an ion approaching towards an ion forms a dipole in an ion then it is known as ion-induced dipole forces.

When a dipole is induced by a polar molecule on an atom or non-polar molecule then it is known as dipole-induced forces.

Intermolecular forces that exists between given molecules is as follows.

(a)  In BrF molecule, there will be existance of dipole-dipole and dispersion forces due to the difference in electronegativity of bromine and fluorine atom.

(b)  In molecule, as there is no electronegativity difference between carbon and hydrogen atom. So, only dispersion forces will exist between atoms of molecule.

(c)   In molecule, there will be existance of dipole-dipole and dispersion forces due to the difference in electronegativity of sulfur and oxygen atom.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.