Identify the type of change : Stretching of a spring *
chemical change
reversible change
irreversible change
Answers
Answer:
reversible change because when we streach the spring it comes back again
Answer:
The molecules of the substances do not change.
Physical changes are reversible, the molecules of the substance remain exactly the same before and after the physical change.
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Question 2:
Growth in plants and animals is
(a) a physical change.
(b) a chemical change.
(c) neither a physical change nor a chemical change since it is a life process.
(d) either a physical change or a chemical change depending on how much the growth is.
ANSWER:
(b) a chemical change
Growth occurs due to the intake of food. The substances present in food are used to nourish the cells and allow them to grow/divide. Hence, growth is a chemical change in which the molecules present in the food undergo changes to form molecules that enhance growth.
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Question 3:
If two substances are brought in contact, it will result in
(a) a physical change only.
(b) a chemical change only.
(c) either a physical change or a chemical change, depending on the conditions.
(d) a chemical change if they are heated together otherwise, a physical change.
ANSWER:
(c) either a physical change or a chemical change, depending on the conditions.
When two substances are mixed together, it can result either in a physical or chemical change. This depends on the substances that are mixed and also on the conditions.
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Question 4:
Chemical changes are
(a) always irreversible.
(b) mostly irreversible.
(c) always reversible.
(d) mostly reversible.
ANSWER:
(a) always irreversible.
Chemical reactions always result in forming new substances with different molecules. It is not easy to get back the original substances. Hence, the chemical changes are permanent and irreversible.
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Question 5:
Which of these is an irreversible change?
(a) melting of ice
(b) melting of wax
(c) boiling of water
(d) burning of wax
ANSWER:
(d) burning of wax.
In the process of burning of wax, it is neither the solid wax nor the liquid wax that is burnt. Wax vapours are burnt giving off heat and light. Once burned, it is not possible to get back the wax. Burning of wax is a chemical process and hence, is irreversible.
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Question 6:
Which of these is a reversible change?
(a) milk turning into curd
(b) burning of wax
(c) melting of wax
(d) rusting of iron
ANSWER:
(c) melting of wax.
The melted wax gets solidified after cooling. The melting of wax, therefore, is a reversible change.
Explanation:
Here is your answers
it's a reversible. change
