Question

FRIST ONE IS THE BRILLIANT



which of the following are chemical changes and which physical give reason​

Answer 1

Answer..

i. physical change

Reason : because it has just broken in this there is no chemical change only its physical appearance had changed.

ii. Chemical change

Reason: when the coal burns it produces carbon gas and it also turns into an ash which is a. Chemical and irreversible change.

iii. Chemical change

Reason: when the cake is being baked then it can't be changed in its raw form. It is a irreversible change that is chemical change.

iv. Physical change

Reason : only its physical appearance has change it can be change into its earlier form.

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Definition

Physical change

It is a type of change which can be reverse through simple physical method. In this change only the physical appearance is changing. No new substance is formed.

Chemical change

It is a type of change which cannot be reverse through simple physical method. In this change the chemical composition of the substance is being change. No substance are being formed.

Answer 2

Physical change :-

Those change in which their is no actual change in its composition, it can be reversed, only physical appearance is change.

ex:- melting of ice.

Chemical change :- Those change in which the composition of matter is change, it cannot be reversed and accompanied with breaking or formation of bonds.

Ex :- Rusting of iron.

1) A glass bottle breaking:- Physical change.Breaking of glass bottles is a physical change because their is no change in actual composition of glass. 2) Coal burning in air → Chemical change. As we know the chemical changes accompanied with evolution of heat and burning of coal produces heat and it's actual composition is also changed. 3) Making a cake →Chemical change.Making a cake is a chemical change because it cannot be reversed again I. e, we can't change cake in to ingredients. 4) Wool being Knitted to sweater → Physical change There is no actual change in its composition and it can be reversed I. e, we can again obtain wool from sweater.