Physical and Chemical Changes

Ramu used chalk powder and made a paste out of it using water. He filled the paste into a mould and sundried it. What change could he observe? If it is a physical change, give reason.

Compare the chemical properties of cooking oil and water.

No new substances are formed during burning of candle.

What are the changes that take place during the burning of a candle?

Which of the following are physical changes?

(a) Melting of iron metal        (b) Rusting of iron

(c) Bending of an iron rod     (d) Drawing a wire of iron metal

A change in the physical state can be brought about 

Assertion (A) : The explosion of a firecracker is a physical change.

Reason (R) : A physical change is a reversible change.

Cooking oil and water are separated by distillation method.

What is the difference between the chemical properties of oil and water?

Cooking oil and water are separated by _____.

How do you separate cooking oil and water?

How do you separate oil from water?

Melting of ice is a physical and chemical change?

What is a chemical change? Give one example.

Open a soda water bottle and place a red and blue litmus paper one by one near the gas coming out of the bottle. Also put both of the litmus paper inside the solution of soda water and observe and note the colour changes of the litmus paper.

Take baking soda in a spoon and test it with wet litmus paper(blue/red). Now heat baking soda in a boiling tube, bring the litmus paper(blue/red) near the gas liberated and note the changes.

Note acidic/basic nature of soda water and baking soda according to the colour change in litmus paper in the table below.

Curdling of milk is an example of _____ change.

State the type of chemical reaction.

$\mathrm{NaOH} + \mathrm{HCl} \to \mathrm{NaCl} + {\mathrm{H}}_2\mathrm{O}$

State the type of chemical reactions.

$2\mathrm{CO} + {\mathrm{O}}_2 \to 2{\mathrm{CO}}_2$

Fill in the blank.

Heating of zinc oxide is a _____ change.

One of the chemical properties of cooking oil is that it is _____.