Define "motif" and explain why one motif in the novel is the scarcity of consumer goods such as butter, razor blades, and real chocolate.Why does...

One question per day, please.  I'll answer the
middle one.

The motif (recurring mini-theme) of
the scarcity of goods is based on the real wartime efforts of the British government
(and U.S., U.S.S.R., and Nazi gov'ts) to both conserve and profit from consumers.
 Remember, this is satire: Orwell is both imitating and exaggerating what he saw
happening during World War II.

Price readjustment is a form
of propaganda that enables the government and manufacturers to both limit the
distribution and control the pricing of necessities (butter) and luxuries (chocolate).
 It's supply and demand, and the war has made supply so low and demand so high that the
prices will, inevitably, become inflated.

The specific
prices or types of goods don't matter as much as what the act and process stands for: it
is a means of information control.  Whatever the government says is a conscious lie.
 The Party lies about the prices; it lies about the scarcity; it lies about who they're
at war with.  It's a means of keeping the Outer Party and Proles hungry, tired, and
stupid.  It's a disinformation campaign against its own people as a means of control and
profiteering.