Mark the incorrect statement.a)Melting of wax is a physical change whi...
Changes which occur again and again after fixed intervals of time are known as periodic changes. For example, change of day and night, occurrence of full moon, beating of heart, oscillation of pendulum of clock, high and low tides in sea, etc. Changes which do not repeat themselves at regular intervals are called non-periodic changes. You cannot predict when will they reoccur. For example, occurrence of earthquake, accidents, sneezing, rusting of iron, growing of a tree, etc.
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Mark the incorrect statement.a)Melting of wax is a physical change whi...
There are four statements given, and we need to identify the incorrect statement. Let's analyze each statement:
a) Melting of wax is a physical change while burning of wax in a candle is a chemical change.
- This statement is correct. Melting of wax involves a change in physical state from solid to liquid, which is a physical change. On the other hand, burning of wax involves a chemical reaction with oxygen to produce heat, light, and various products, which is a chemical change.
b) Metals expand on heating while contract on cooling. Both are physical changes.
- This statement is correct. When metals are heated, their particles gain kinetic energy and vibrate more, causing the metal to expand. This expansion is a physical change. When the metal is cooled, the particles lose kinetic energy and vibrate less, causing the metal to contract. This contraction is also a physical change.
c) Composition of matter changes during a chemical change while it remains the same during a physical change.
- This statement is correct. In a chemical change, new substances are formed with different compositions than the original substances. The atoms rearrange to form new compounds, resulting in a change in composition. In contrast, during a physical change, the composition of matter remains the same even though there may be a change in physical state or appearance.
d) High and low tides in the sea are examples of non-periodic changes while the growth of a tree is a periodic change.
- This statement is incorrect. High and low tides in the sea are actually examples of periodic changes. Tides are caused by the gravitational pull of the moon and the sun on the Earth's oceans, resulting in regular and predictable patterns of high and low water levels. These patterns repeat approximately twice a day. On the other hand, the growth of a tree is a continuous and ongoing process, which does not occur at regular intervals. It is not a periodic change.
Therefore, the incorrect statement is option D.
Mark the incorrect statement.a)Melting of wax is a physical change whi...
Answer a
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