Question

Which statement is true about physical changes and chemical changes?

A) physical changes can change both physical and chemical properties.

B) chemical changes are not observable.

C) chemical changes always produce new substances.

D) physical and chemical changes cannot happen at the same time.

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Answer 1

Answer:

c is the correct option

Explanation:

chemical changes always produce a new substance

Answer 2

The true statement about physical changes and chemical changes is- C) chemical changes always produce new substances.

There are two types of change in nature- physical change and chemical change.

Physical change

• It is a temporary change in which no new substances are formed but only the physical properties of substances are changed.
• Melting of wax is an example of physical change in which no new substance is formed but only shape is changed.

Chemical change

• It is a permanent change in which new substances are formed due to chemical reactions that changes the chemical composition of the substance.
• The burning of wood is an example of chemical change in which gases are released into the atmosphere and a new substance i.e. ash is formed.
• We can observe the chemical change by the change in colour, odour and temperature of the substance. The evolution of gas also confirms that a chemical change has occurred.

Note: During the burning of candle both physical and chemical changes occur. When the wax melts due to heat, a physical change occurs while the burning of the candle releases gases such as carbon dioxide into the atmosphere which is a chemical change.