Physical and Chemical Changes Class-7th Goyal Brothers Chemistry Solutions Chapter-2. We Provide Step by Step Answers of Objective, True False , Fill in the blanks, Match the following , Study Questions of Chapter- 2, Physical and Chemical Changes. Visit official Website CISCE for detail information about ICSE Board Class-7.
Physical and Chemical Changes Class-7th Goyal Brothers
Chemistry Solutions Chapter-2
| Board | ICSE |
| Class | 7th |
| Subject | Chemistry |
| Book Name | Goyal Brothers |
| Theme-2 | Physical and Chemical Changes |
| Unit-1 | Physical and Chemical Changes |
| Topic | Solution of exercise questions |
| Session | 2023-24 |
OBJECTIVE TYPE QUESTIONS
Chemistry Solutions Chapter-2
A. Fill in the blanks :
- Heating of zinc oxide is a _physical_ change.
- Burning of coal is a _chemical_ change.
- There is a change in state and _composition_ during a chemical change.
- Plants make their food by the process of _photosynthesis_.
- _Heat_ energy is generally given out or absorbed during a chemical change.
B. Statement given below are incorrect. write the correct correct statement:
1. A physical change cannot be reserved.
Correct Statement: A chemical change cannot be reserved.
2. During a chemical change there is no change in weight.
Correct Statement: During a chemical change there is no change in mass.
3. During a physical change new products are formed.
Correct Statement: During a physical change no new products are formed.
4. Glowing filament of an electric bulb is an example of a chemical change.
Correct Statement: Glowing filament of an electric bulb is an example of a physical change.
5. Formation of frost during winter is an example of a chemical change.
Correct Statement: Formation of frost during winter is an example of a physical change.
C. Match the statement in Column A with those in Column B:
Column A |
Column B |
1. Crushing of an ice cube. |
(a) Heat |
2. Making of curd from milk. |
(b) Physical change |
3. Plants making their food during sun-shine. |
(c) Rusting |
4. The energy given out/absorbed during a chemical change. |
(d) Photosynthesis |
5. Iron get coated with a brown powdery deposit in moist air. |
(e) Chemical change |
Answer:
Column A |
Column B |
1. Crushing of an ice cube. |
(b) Physical change |
2. Making of curd from milk. |
(e) Chemical change |
3. Plants making their food during sun-shine. |
(d) Photosynthesis |
4. The energy given out/absorbed during a chemical change. |
(a) Heat |
5. Iron get coated with a brown powdery deposit in moist air. |
(c) Rusting |
D. Write ‘True’ or ‘False’ for the following statements :
- Digestion of food is a chemical change. [T]
- Formation of steam from water is a physical change. [T]
- During a chemical change, molecular composition remains same. [F]
- During a physical change, the state and the composition of a substance change. [T]
- When copper sulphate dissolves in water, chemical change takes place. [F]
E. Tick (√) the most appropriate answer.
1. Chemical changes are the result of absorption or release of :
(a) Heat energy only
(b) light energy only
(c) sound energy only
(d) Some kind of energy
Ans: (a) Heat energy only
2. A chemical change involves :
(a) Change of state only
(b) Change of colour only
(c) Change in state as well as composition
(d) none of these
Ans: (b) Change of colour only
3. A physical change is a :
(a) Temporary change
(b) Permanent change
(c) Temporary change which can be reversed
(d) None of these
Ans: (c) Temporary change which can be reversed
4. An example of a physical change is :
(a) magnetism of iron
(b) burning of wood
(c) photosynthesis by plants
(d) digestion of food
Ans: (a) magnetism of iron
5. An example of a chemical change is :
(a) exposing photographic film to sunlight
(b) tearing of paper
(c) melting of butter
(d) formation of clouds
Ans: (a) exposing photographic film to sunlight
STUDY QUESTIONS
Chemistry Solutions Chapter-2
Question 1.
(a) Define ‘ Physical change ‘.
Answer: A physical change is a temporary change in which no new substance is formed
(b) Give four examples of physical change.
Answer: Four Examples of physical changes are boiling water, crushing a can, melting ice, dissolving salt/sugar in water.
Question 2.
(a) Define ‘ chemical change ‘.
Answer: The chemical composition of the original substance remains the same, even though its physical. properties like colour, state, shape, size etc.
(b) Give four examples of Chemical change.
Answer: Examples of chemical changes are burning, cooking, rusting, and rotting.
Question 3. Classify the following as physical change or chemical change.
(a) Burning of wood= Chemical change.
(b) Glowing of an electric bulb= Physical change
(c) A magnet attracting iron nails= Physical change
(d) Burning of magnetism ribbon in air= Chemical change
(e) Photosynthesis in plants= Chemical change.
(f) Moulding of glass= Physical change.
(g) Formation of fog= Physical change.
(h) Digestion of food= Chemical change.
Question 4. State four difference between a physical change and chemical change.
Answer: Four difference between a physical change and chemical change are:-
| Physical change | Chemical change |
| 1. In a physical change no new substance is formed. | 1. In a chemical change new substance is formed |
| 2. Temporarily change which can be reversed | 2. Permanent change and irreversible |
| 3. Weight of original substance doesn’t change | 3. Weight of original substances may increase or decrease |
| 4. Energy like heat, light etc. may or may not be absorbed or released | 4. Energy like heat, light etc. are given out or absorbed. |
Question 5. State the types of change involved when there is a change of state of matter
Answer: A change of state is a physical change in a matter. They are reversible changes and do not involve any changes in the chemical makeup of the matter. Common changes of the state include melting, freezing, sublimation, deposition, condensation, and vaporization.
Question 6. State the types of change involved when there is a change of energy by giving proper example.
Answer: Whenever there is any physical or chemical change takes place, energy is involved. Either the energy is absorbed or released in one form to other. The changes involve absorption of energy are known as endothermic changes. Example, Cooking of food or melting of ice needs heat energy, therefore, they are endothermic changes.
The changes that involve evolution or release of energy are known as the exothermic changes. Example, burning of match sticks.
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