Answer:- (i) phosphorous and chlorine is polar covalent.
(ii) potassium and oxygen is ionic.
(iii) fluorine and fluorine is nonpolar covalent.
(iv) copper and aluminum is metallic.
(v) carbon and fluorine is polar covalent.
(vi) carbon and hydrogen is nonpolar covalent.
(vii) Aluminum and oxygen is ionic.
(viii) silver and copper is metallic.
Explanations:- An ionic bond forms between a metal and a non metal by the transfer of metal atom valence electrons to the non metal. In (ii) and (vii) the bond is between a metal and a non metal. Potassium is a metal and oxygen is non metal, so the bond between them is ionic. Similarly, Aluminum is a metal and oxygen is a non metal, so the bond between them is also ionic.
Metallic bond is formed between metals only. In (iv) we have metals copper and aluminum and in (viii) we have metals silver and copper. So, there would be metallic bond only.
Covalent bond is formed by the sharing of electrons between non metals. If the bond is between two similar non metals for example H and H, Cl and Cl, N and N etc then it is known as nonpolar covalent as the shared electrons are between both the non metals.
If the bond is formed between two different non metals like C and F, H and Cl etc then it is known as polar covalent as the shared electrons are more towards the more electron negative atom and due to which the highly electron negative atom has partial negative and the less electron negative atom has partial positive charge.
Note:- Even if the bond is between two different non metals but the electron negativity difference is too low then it is considered as nonpolar covalent.
Electron negativity difference between C and H is very low and so the C-H bond is considered as nonpolar covalent.
