for 3a why does Ba(Cn)2 have ionic and covalent bonds present

and please answer 3b in full detail

3. (a) A similar chemical species is formed when Ba is in the presence of C and N, Ba(CN) 2. Once again, all atoms obey the octet rule. Explain why you would say the type of bonding does not change. 3. (b) Explain why more C and N atoms are required to form a compound with Ba. It is important to note that all atoms obey the octet rule. Hint generate the Lewis diagram for Ba(CN)2 to help you answer this