Question

Short answer type questions.
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(a) Give two examples where expansion and contraction of metals is utilised.
(b) Chemical changes are irreversible. Justify the statement by giving two examples.
(c) Give an example of a change caused by mixing of things.
(d) Why is melting of butter said to be a physical and reversible change?
(e) Why is folding of a paper said to be a physical change?
(f) Most physical changes are reversible. Justify the statement by giving two
examples.
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Answer 1

Answer:

2) The steel developed to reinforce concrete has the same expansion as the concrete. 3) Concrete roads are poured with expansion joints between the slabs to allow for thermal expansion (these joints are the cause of the thumping noise commonly experienced when traveling on a concrete highway).