Question

49. An iron rim is made slightly smaller than the wooden wheel (around which it is to be
fitted). The iron rim is heated uniformly due to which it undergoes a change P and
can be easily put around the wooden wheel. When cold water is poured over this hot
iron rim, it undergoes another change Q and fits tightly over the wooden wheel. After
a considerable time, a change R takes place in the iron rim due to which a red-brown
coating is formed on it.
a) What are the changes P, Q and R?
b) Out of P, Q, and R which change/changes is/are reversible?
c) Write three difference between P and R.​

Answer 1

Answer:

a) P - expansion

Q - contraction

R - rusting

b) P and Q

c ) p is a reversible change , R is irreversible

in p no new substance is formed , new substances is formed ( dull layer) - R

p - it takes place because molecules contract , r - it takes place because of action of air and water vapour in the air

Explanation:

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Answer 2

Answer:

Explanation:

P EXPANSION

Q contraction R rusting