Answer is: 4. NaCN. Ionic bond Is between sodium cation Na+ and cyanide anion CN-. Covalent bond Is between carbon and nitrogen. Sodium cyanide Is white solid salt, dissolved in water and very toxic. With acids gives HCN.
NaCn contains an Na+ ion and a CN- negative ion, so it has an ionic bond. The CN ion is formed by a covalent bond of the carbon and nitrogen, so it also has a covalent bond. Therefore, the answer is NaCN.
