What happens when a wave hits a barrier with a single opening? ?

The electrical conductivity of a metal depends on the free electron concentration.A substance having more number of free electrons in its conduction band has more conductivity than others.

Free electrons are these electrons which experience less or negligible force from the nucleus of an atom.In case of metals, the valence band and conduction band are either overlapped or they have a small forbidden energy gap.Hence,the metal having large number of valence electrons will be responsible for higher conductivity of the specimen.

The atomic radius also plays a crucial role in determining the conductivity of a metal.In case of metals whose atoms have lesser atomic radius,the nucleus exerts higher amount of attractive coulombic force on electrons.Hence the electron can not be free.Larger the atomic radius,the lesser will be the force of attraction of nucleus on the electrons.Hence,the availability of free electrons will be more.

Hence the correct option will be A.more valence electrons and larger atomic radius