Describe the physical properties of $B$ and $Al$.

(N/A) Properties of $B$: $(i)$ $B$ has a high melting point,low density,and very low electrical conductivity.
$(ii)$ It is an extremely hard,high-temperature resistant solid element.
Properties of $Al$: $(i)$ It is a silvery-white lustrous metal.
$(ii)$ It possesses high electrical and thermal conductivity.
$(iii)$ By weight,$Al$ has twice the conductivity of $Cu$.