Physical and Chemical Changes

Q.

What are slow and fast changes? Give examples.

Q. What happens when lemon juice is mixed with baking powder? Is it a physical change or a chemical change? How?

Q. Salt can be separated from its solution (salt dissolved in water) because

1. mixing of salt in water is a change that can be reversed by heating and melting of salt.
2. mixing salt in water is a change that cannot be reversed.
3. mixing salt in water is a permanent change.
4. The mixing of salt in water is a change that can be reversed by evaporation

Q. What are physical and chemical changes ? What is the difference between them?

Q.

Which one is chemical change rusting of iron or melting of iron.

Q.

$$\begin{gathered} {\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\left(\mathrm{aq}\right)+6{\mathrm{O}}_2\left(\mathrm{g}\right)\to 6{\mathrm{CO}}_2\left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+∆ \\ \mathrm{Glucose}\mathrm{Oxygen}\mathrm{carbon}\mathrm{water}\mathrm{heat} \\ \mathrm{dioxide} \end{gathered}$$

The above reaction is__________________________

Q. Is melting of wax a physical or a chemical change?

Q.

Sublimation of camphor is an example of ____ change.

Q.

Classify the following as chemical or physical changes: Melting of butter in a pan?

Q.

Which of the following are pure substances?

Milk, iron , hydrochloric acid , mercury , wood , air.

Q. Consider the reaction 2A to 3B + C. Starting with pure A initially the total pressure doubled in 3 hours . What can be the order of reaction

Q.

How is the souring of milk a chemical change?

Q.

Define a slow change with an example.

Q.

Write T for true and F for false statements.

Physical changes are reversible.

1. True
2. False

Q.

Explain the pure substance by giving examples.

Q.

Give two examples of the following change occurring during a chemical reaction:

Change of colour

Q.

Water cycle is a natural change.Classify it as a physical or chemical change and reversible or irrerviersible change .Justify your statement.

Q.

What happens to the chemical composition of a substance that undergoes a physical change?

Q.

How can we check the purity of liquids?

Q. is not a chemical change occuring in human body.

1. Digestion of food
2. Getting a papercut
3. Production of hormones

Q.

Rusting of iron is slow change.

1. True
2. False

Q.

State the characteristics of physical change and chemical change.

Q. Assertion :"A golden yellow precipitate of lead iodide is formed when colourless lead nitrate solution is mixed with colourless solution of potassium iodide." So, it is a chemical change Reason: Formation of new products in the reaction with the precipitate indicates a chemical change

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q. Matter undergoes a change. The changes are of two types: Physical and chemical change.

1. Chemical only
2. Physical only
3. Both chemical and physical
4. Neither chemical nor physical

Q.

Iron and phosphorus powder are mixed together to form a magnetic black and red mixture. This is a

1. Irreversible change

2. Physical change

3. No change

4. Chemical change

Q. A farmer has sown seeds in his field, after sometime the seeds have grown into a crop. What kind of change is growing of seeds into a crop, is it man made or natural. Explain

Q. Copper sulphate when reacts with iron, changes its colour from blue to green. This is a:

1. both A and B
2. physical change
3. neither A nor B
4. chemical change

Q.

Curdling of milk is physical or chemical changes.

Q.

2) Classify the following as physical or chemical changes:

d) Burning of magnesium ribbon in the air

Q. Define a pure substance. How many types of pure substances do you know?​