Step-by-step explanation:

A substance kept in first aid kit expand when heat is provided to it.

Answer:

(1−i)4=[(1−i)2]2

=[12+i2−2i]2

=[1−1−2i]2

=(−2i)2

=(−2i)×(−2i)

=4i2=−4,[∵i2=−1]

=a+ib, where a=−4, and b=0