Which of the following statements is incorrect about physical changes?...
Explanation:
Physical changes are changes in the physical properties of a substance, such as shape, size, state, or appearance. They do not involve any change in the chemical composition of the substance. Some common examples of physical changes are melting, freezing, boiling, condensation, sublimation, and dissolution.
Now, let us analyze the given statements one by one:
a) There is no gain or loss of energy: This statement is correct. Physical changes do not involve any change in the energy of the substance. The energy may be required to carry out the change, but it is not gained or lost by the substance itself.
b) It is permanent and irreversible: This statement is incorrect. Physical changes are usually temporary and reversible. For example, if we melt an ice cube, it will turn into water, but we can freeze the water again to get back the ice cube. Similarly, if we dissolve salt in water, we can evaporate the water to get back the salt.
c) Composition of the substance remains the same: This statement is correct. Physical changes do not involve any change in the chemical composition of the substance. The atoms or molecules of the substance remain the same before and after the change.
d) No new substance is formed: This statement is correct. Physical changes do not involve any chemical reaction, so no new substance is formed. The substance may change its state or appearance, but it remains the same substance.
Therefore, the correct answer is option 'B' which says that physical changes are permanent and irreversible. In reality, physical changes are usually temporary and reversible.
Which of the following statements is incorrect about physical changes?...
Physical change can be reversed in it's original form so it is temporary not permanent and not irreversible.
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