State whether the following statements are true or false. Rewrite the false ones correctly.
(a) All irreversible changes are chemical changes.
(b) A liquid can sublime.
(c) The evaporation of water take place only at 100°C. when it is boiling.
(d) The melting of ice is a physical change.
(e) The souring of milk is a periodic change.
(f) The flowering of trees is a periodic change.
(g) Solidification and condensation are the same.
(h) The breaking of glass tumbler is a chemical change because it is irreversible.
(i) Boiling, evaporation and condensation are physical changes.

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Solution

(a) False. Some physical reactions are also irreversible like breaking of bat.
(b) False. Liquid vaporises.
(c) False. Evaporation can take place at variable temperatures.
(d) True.
(e)False. It is a non-periodic change.
(f) True
(g)False. They are different. Solidification is the conversion of liquid into solid, whereas condensation is the conversion of gas into liquid.
(h)False. It is a physical change.
(i)True.

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