Question

why is CuCl2 more covalent than NaCl

Answer 1

 This is due to for two cations with similar size;the cation with a pseudo noble gas configuration has more polarizing power than the other due to which its compound with the same anion is more covalent.Cu^+ &Na^+ have similar sizes but Cu^+ ion has pseudo noble gas configuration 1s²2s²2p^63d^10 due to which it has more polarizing power than Na^+ ion.Thus,CuCl has more covalent character than NaCl.