State Four Differences Between Physical and Chemical Changes.

State four differences between physical and chemical changes.

Distinguish Between

Physical change	Chemical change
No new substances with new properties are formed. It can be reversed by simple physical methods. It is temporary change. Energy is neither needed nor produced.	New substances with new properties are formed. Change cannot be reversed by simple physical methods. It is permanent change. Energy is either needed or evolved.

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Chapter 2: Physical and Chemical Changes - Exercise

Chapter 2 Physical and Chemical Changes
Exercise | Q 7

Name a chemical change which takes place in presence of:

State whether the following is physical or chemical changes.

shaping a piece of glass —

A physical change is temporary. Explain.

Fill in the blank.

A change, which alters the composition of a substances, is known as a___________ change.

Match the examples of changes in List I with the correct.

List I	List II
1. Expansion of a steel rod on heating	A: Physical change
2. Rotting of eggs	B: Chemical change
3. Milk turning sour
4. Tarnishing of copper
5. Separation of naphthalene from a mixture of naphthalene and sodium chloride.

Potassium chloride is added to water and stirred. A salt solution is obtained, which is then boiled, leaving behind a residue.

Is the above change physical or chemical?
Name the residue which remains behind after the salt solution is boiled.
Is the change reversible or not reversible?
Are the composition and properties of the original substance altered?
Give a reason why the above experimentation would not be possible if calcium carbonate was taken in place of potassium chloride.

Give the reason why the following is considered as chemical changes.

A bright light is seen evolved when a strip of magnesium is heated.

When ice melts to form water, change occurs in its

Sublimation of Iodine is a ______.

A physical change is generally____________.