NCERT Solutions for Class 7 Science Chapter 6: Physical and Chemical Changes

NCERT Solutions for Class 7 Science Chapter 6 Physical and Chemical Changes are provided in the article below. The important topics covered in this chapter are:

• Physical changes
• Chemical changes
• Rusting of iron
• Crystallization

Download PDF: NCERT Solutions for Class 7 Science Chapter 6 Physical and Chemical Changes

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NCERT Solutions for Class 7 Science Chapter 6

NCERT Solutions for Class 7 Science Chapter 6 Physical and Chemical Changes are given below:

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Class 7 Science Chapter 6 Physical and Chemical Changes: Important Topics

A Physical change is a temporary change that affects only physical properties such as shape, and size. It is said that, whenever a substance goes through a physical change, its composition remains the as it is despite its molecules being rearranged. A chemical change is a permanent change having both physical and chemical properties of a substance. It is said that whenever a substance goes through a chemical change, its molecular composition is completely changed.

• Physical changes

Physical changes are defined as the changes affecting the form of a chemical substance, but not it is chemical composition. Physical changes are generally used to separate mixtures into their component compounds, but can not be used to separate compounds into chemical elements or simpler compounds.

• Chemical changes

Chemical changes take place when a substance combines with another in order to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are known as chemical reactions which, in general, are not reversible except by further chemical reactions.

• Rusting of iron

Rusting of iron is an oxidation reaction. The iron reacts with water and oxygen in order to form hydrated iron(III) oxide, which we perceive as rust. Iron and steel rust when they come into contact with water and oxygen – both are needed for rusting to occur.

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