(a) Copper cannot displace hydrogen from an acid because copper is less reactive element than hydrogen and it is present below hydrogen in the activity series of metals.
(b) Transition metals and many other metals shows paramagnetic behaviour because they posses number of unpaired electrons in d-orbital.
(c) Metal atoms like Zn,Cd,Hg have completely filled d-orbitals ( d10 configuration). Thus, d-electrons are not available for metallic bond formation. As a result, these metals are quite soft and also have low melting points.