Question

3.why a sublimation a physical change? 4. What are the characteristics of a chemical change?​

Answer 1

3. Yes, sublimation is a physical change because it involves a change of state from solid to gas of a substance when it is heated.

4.

• Evolution of gas.
• Formation of a precipitate.
• Change in color.
• Change in temperature.
• Change in state.
• Formation of new substances.

Answer 2

Answer:

Explanation:

3. sublimation is a physical change because it is just the change of a solid substance to it's vapour state,no new substance is formed and it can be again converted to solid this means it is a reversible change whereas in case of slaking of lime CaO reacts with H2O to form Ca(OH)2

and energy,a new substance Ca(OH)2

is formed and it can't be reversed by physical means so,it's a chemical change.

4. The characteristics of a chemical reaction are :

Evolution of gas.

Formation of a precipitate.

Change in color.

Change in temperature.

Change in state.

Formation of new substances.

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