what is physical change, chemical change, slow change, fast change, periodic change, non-periodic change,  desirable change and undesirable change ?

1) Some changes affect only the physical properties of the substance that is undergoing change. Physical properties include shape, size, colour and state of matter.

  • Some properties of physical changes are:

A physical change is temporary.
No new substance is formed when a physical change takes place.
Forms of energy, such as heat, light and electricity, are neither emitted nor absorbed in a physical change.
A physical change is generally reversible

2)Some changes are in the form of chemical reactions, which lead to the formation of new substances. These are called chemical changes. These changes may be accompanied by the emission of heat, light or sound, a change in colour, or the formation of a gas.

  • Some properties of chemical changes are:

A chemical change is permanent.
new substance is formed. 
Forms of energy, such as heat, light or electricity, may be emitted or absorbed during a chemical reaction.

A chemical change is generally irreversible.

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3) desirable change is one that you do want, or desire. eg rain on a hot summer day

4)An undesirable change is one that you have not expected and is unwanted.eg.breaking of toys.

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 a change that repeats itself ater fixed intervals of time is called a periodic change.eg day and night

 a change that repeats itself but time is not fixed is called a non peridic change.eg sneezing.

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 a change that takes place very fast is known as a fast change.

 a change that takes place slowly is known as a slow change.

 Fast changes - a thunderstorm, a flash flood, a landslide, an earthquake, a volcanic eruption.

Slow changes - erosion by wind or rain, mountain formation, glaciers, tectonic plate movement, the seasons.

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Hi Arnab!

Please refer to the answers given by Prakhar.

Good work @Prakhar!! Keep writing!!


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