(i) Mutual inductance decreases.
(ii) Mutual inductance increases.
(iii) Concept: (i) If distance between two coils is increased as shown in figure.
It causes decrease in magnetic flux linked with the coil C2. Hence induced emf in coil C2 decreases by relation Hence mutual inductance decreases.
(ii) From relation M21 = µ0 n1 n2 Al, if number of turns in one of the coils or both increases, means mutual inductance will increase.