How can you say these are chemical change?Give one reason for your answer.
(a) Burning of candle.
(b) Milk sours in hot and humid weather.
(c) Decomposition of water into hydrogen and oxygen.
(d) Rusting of iron.
(e) A frog breaths heavily.
Answers
Answer:
once they are changed they can't come back to their original shapes and hence they are called chemical changes
Explanation:
burning of candle will change into wax
Explanation:
a) burning of a candle is a chemical change because burning is always a chemical change and when a candle burns produces flame which is a new burning is always a chemical change and when a candle burns produces Ashes and heat which are new substances
b) milk size in hot and humid weather due to the formation of lactobacillus in it which forms curd so the new substance is formed which makes it a chemical change.
c) decomposition of water into hydrogen and oxygen is not a chemical change because it is reversible in nature.
d) rusting of iron is a chemical change because interesting of iron iron changes into iron oxide which is a new substance and this change is not reversible in nature.
e) breeding of frog is a chemical change because when it breathes his body makes energy out of the food he ate and the air it took.