Physical and Chemical Changes

Q.

1g of copper powder was taken in a china dish and heated. What change takes place on heating?

When hydrogen gas is passed over this heated substance, a visible change is seen in it.

Give the chemical equation of reactions, the name, and the colour of the products formed in each case.

Q.

Define physical change?

Q. what is the order of melting and boiling points in the 13^{th} group

Q. Which of the following is/are example(s) of physical change?

1. interconversion between states of matter
2. breaking a glass
3. burning of coal
4. digestion of food

Q.

Which of the following is not a physical change?

1. Boiling of water to give water vapor

2. Melting of ice to give water

3. Dissolution of salt in water

4. Combustion of Liquefied Petroleum Gas (LPG)

Q.

When wax is burnt (in the form of a wax candle), then water and carbon dioxide are formed. This shows the "change in state" characteristic of reactions.

1. True

2. False

Q.

Is sublimation a chemical change or physical change? What about sublimation of ammonium chloride?

Q.

Rusting of iron is faster in saline water than ordinary water. Why?

Q. Question 16

Which one of the following processes involves chemical reactions?

(a) Storing of oxygen gas under pressure in a gas cylinder.
(b) Liquefaction of air.
(c) Keeping petrol in a china dish in the open.
(d) Heating copper wire in presence of air at high temperature.

Q.

What is called physical change and chemical change?give examples for the following?

Q.

Classify the following, as a physical or a chemical change. Give reasons: Churning of milk cream to get butter?

Q. Question 1

Which of the following is not a physical change?

(a) Boiling of water to give water vapour
(b) Melting of ice to give water
(c) Dissolution of salt in water
(d) Combustion of Liquefied Petroleum Gas (LPG)

Q.

We say that cooking is also a chemical reaction.so when we cook something we provide heat.and when food is ready it produces heat.

Which type of reaction is this

Chemical or physical?????

Q.

$\underset{\left(\mathrm{Iron}\right)}{4\mathrm{Fe}\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Oxygen}\right)}{3{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{(\mathrm{Iron}\mathrm{oxide})}{2{\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)}$. The above reaction takes place in the presence of ______________.

Q.

10. The boiling of rice is a physical change.

1. True
2. False

Q.

A Chemical change is also known as a chemical reaction.

1. True
2. False

Q.

Two drops of dilute sulphuric acid were added to 1 g of copper sulfate powder and then a small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue-colored crystals got separated (step II). Step I and Step II are:

1. physical and chemical changes, respectively

2. chemical and physical changes, respectively.

3. both physical changes.

4. both chemical change

Q.

List the characteristics of physical change. Give any two examples of physical change?

Q.

Rusting of iron is a chemical change because

1. a new substance with new properties is produced.

2. the chemical composition of reactant is changed.

3. the change is permanent and cannot be reserved easily.

4. all of these

Q.

Iron nails do not get rusted when kept in distilled water even for a long time. Assign reason.

Q.

Why is heating an Iron rod a physical change?

Q.

Question 29
Grapes hanging on the plant do not ferment but after being plucked from the plant can be fermented.

Under what conditions do these grapes ferment? Is it a chemical or a physical change?

Q.

Which of the following feature is common to both physical and chemical change?

1. Evolution of hydrogen gas

2. Formation of new precipitate

3. Change in state and colour

4. Evolution of carbon dioxide

Q. Which of these given options is/are properties of a chemical change?

1. Both physical and chemical properties are changed.
2. New substances are formed.
3. Both a and b.
4. Neither a nor b.

Q.

Freezing of water is a:

1. Physical change

2. Chemical change

3. Both physical and chemical change

4. Exothermic reaction

Q.

A chemical change may involve –

1. change in color only

2. change in temperature only

3. evolution of gas only

4. any or all of the above

Q.

Can rusting of Iron take place in distilled water?

Q.

Permanent Change Is?

1. Chemical Change

2. Physical Change

3. Both (A) And (B)

4. None Of These

Q. In the process of rusting, the metal Iron (Fe) reacts with which substances present in the atmosphere? Write an equation for the process. [2 MARKS]

Q.

1. Observe the following changes and mention the type of change in shape, size, color of state.

Name of items	How item changed
1. Ripening of fruit
2. Burning of candle
3. Kneading flour
4. Souring of milk
5. Moulding clay