CBSE Chemistry 7th Acids bases and Salts [Solved]

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Q. Why is calamine solution put on the ant sting? 
Ans. When an ant bites, it injects formic acid into the skin. The effect of acid can be neutralized by applying calamine solution which is basic in nature. 

Q.Sometimes we treat the soil with bases. Give reasons why? 
Ans. Excessive use of fertilizers makes the soil acidic, which is not suitable for the growth of the plants . Hence we treat the soil with bases like calcium oxide to neutralize of acid. 

Q.The factory waste is treated with basic substances before disposing it? 
Ans. The wastes of factories contain acids. If they are allowed to flow into the water bodies, then they are harmful to the aquatic life. Therefore, factory waste are treated with basic solutions. 

Q.What is the chemical name of the following: 
Common name      Chemical name 
Quick lime             Calcium oxide 
Slaked lime           calcium hydroxide 
Baking soda         sodium hydrogen carbonate 

Q. What is the chemical composition of milk of magnesia? 
Ans. The chemical composition of milk of magnesia is magnesium hydroxide. 

Q. What is the chemical composition of calamine solution? 
Ans. The chemical composition of calamine solution is zinc carbonate.

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Related study materials

MCQ:Acid base and salt: For Olympiads-1 

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7th Heat and Temperature [Formative Assessments -01]

1. Radiation

(a) does not require any medium

(b) is the process of transfer of heat in liquids

(c) is the process of transfer of heat in which heat traveles in one direction.

(d) Occurs in solids.

2. A Thermos flask prevents loss or gain of heat by

a. conductions only

b. convections only

c. radiation only

d. all the above


3. Handles of cooking utensils should be made of material that

a. conducts heat well

b. does not conduct heat

c. radiate heat well

d. does not radiate heat

4. Sea breeze and land breeze

a. are caused by currents set up in air due to conduction

b. are caused by currents set up in air due to convection

c. are caused by currents set up in air due to radiation

d. have no relation to conduction, convection and radiation

5. Which of the following is the best heat insulator

a. air

b. steel

c. copper

d. iron

6. Heat from the sun reaches us by the process of

a. conduction

b. convection

c. radiation

d. all the above


7. In liquids heat is transferred

a. only by convection

b. only by radiation

c. mainly by conduction and convection

d. none of these

8. Stainless steel pans are provided with copper bottom because

a. copper is easier to clean than stainless steel

b. such pans are colourful

c. copper bottom makes the pan more durable

d. copper is better conductor of heat than stainless steel

9. A polished silvery surface is

a. good absorber of heat

b. good reflector of heat

c. poor reflector of heat

d. None of these

10. Land breeze blows in coastal regions during

a. day

b. summer

c. winter

d. night

11. A wooden spoon is dipped in a cup of icecream. Its other end

a. does not become cold

b. becomes cold by the process of radiation

c. becomes cold by the process of convection

d. becomes cold by the process of conduction

12. Dark coloured clothes are preferred during

a. summer (b) sand storm  (c) winter (d) none of these

13. A black body with rough surface is a

a. good reflector and poor absorber of heat

b. good absorber and good radiator of heat

c. good absorber and poor radiator of heat

d. good reflector and poor radiator of heat

14. Range of laboratory thermometer is generally from

a. -10 F to 110 F

b. 10 C to 110 C

c. 10 C to -110 C

d. -10 C to 110 C

15. Normal temperature of human body is

(a) 37 F (b) 37 C (c) 39 C (d) 39F

16. Which of the following is a good conductor of heat

(a) Wool (b) Water (c) Wood (d) Silver

17. Device used for measuring temperature

(a) Barometer (b) Odometer (c) Thermometer (d) Speedometer

18. Transmission of heat energy with actual movement of particles

(a) Conduction (b) Convection (c) Radiation (d) None of these.

19. When two bodies are kept in contact heat flows from

a. a body at higher temperature to the body at lower temperature

b. a body at lower temperature to the body at higher temperature

c. no flow of heat

d. all of the above

20. A cold steel spoon dipped in a cup of hot milk. It transfers heat to the other end by the process of

(a) radiation (b) convection (c) conduction (d) none of these

1. a       2. d           3. b         4. b         5. a            6. c      7. a        8. d      9. b         10. d        11. a      12. c           13. b    14. d        15. b       16. d       17. c    18. b     19. a  20. c 

8th Science Power -Conservation of Plants and animals

Formative and summative assessments-   8^th Science Power

Topic For Group discussion:

Q. Saving paper helps to conserve our natural resources.

Organize a seminar on the topic: Flora and fauna and its diversity.

Prepare a project report on the wild life which has reached on the verged of extinct.

General Questions:

1. Define these terms:

a. Flora:

The plants found in a particular area is called flora of that area

b. Wild life sanctuary

Wildlife sanctuaries is protected area reserved for wild animals, birds and plants

c. Biosphere reserve

The protected area in which multiple use of land is permitted to conserve biodiversity.

d. Fauna

The animals found in a particular area are called fauna of that area.

2. Differentiate between the following:

a. Endangered and Extinct species

b. Endemic and exotic species

3. Answer these Questions:

a. What is red Data book?

Answer: Red data book contain a record of all those species of plants and animal which are under the threat of extinction or are rare and vulnerable for extinction.

b. Define deforestation and Afforestation and Give consequences of deforestation?

Answer: Deforestation is the practice of cutting down of trees whereas the practice of planting more trees is called Afforestation.

Following are the consequences of deforestation:

a. Global warming

b. Climatic change

c. Desertification

d. Drought and flood

e. Soil erosion and loss of wild life

c. Mention the effect of deforestation on environments, wild animal and soil?

Answer: The effect of deforestation on environments: Deforestation increases the temperature and wind speed which causes global warming.

d. Why is tiger an endangered species?

Answer: Tiger is an endangered species because tiger will soon became extinct if the same causative factors continue.

e. What are the major threats to wild life?

Answer: Following are the major threats to wild life:

(i) Habitat loss (ii) Indiscriminate killing and poaching (iii) pollution of air water and soil pollution

f. Why biosphere reserve the best way of wild life conservation?

Answer: This is because biosphere reserves not only help in maintaining the biodiversity but also create awareness to maintain culture of that area.  

g. Human population is a threat to biodiversity? Justify?

Answer: Human population is a threat to biodiversity because more and more land of forest is cleared to fulfill the needed of growing population.

h. List major steps taken by government to conserve biodiversity in India?

Answer: Following are the major steps taken by government to conserve biodiversity in India:

(i) Creation of protected area like park sanctuaries and biosphere reserve

(ii) Making strict low to prevent poaching

(iii) Making captivity for breading

(iv) Starting project to save endangered animals

i. Write notes on (i) project tiger (ii) Gir lion project

Answer: (i) Project Tiger: Project tiger is a program launched by government that saves tiger from poaching by making 23 tiger reserve.

(ii) Gir lion project :  Gir lion project started by Gujarat government in 1972 to protect Asian lion.

j. What does IUCN Stands for?

Answer: IUCN Stands for The international Union for Conserve of Nature and Natural Resources.

k. What do you know about Chipko movement?

Answer: Chipko movement is started by Sundar Lal Bahuguna in Uttarakhand to save tree.  The women of village embraced the tree and protest cutting of tree.

Hots Questions:

1. Why rainfall reduced in Cherrapunji which once had the highest rain fall?

Answer: Rainfall in Cherrapunji greatly reduced by loss of forest cover to create space for growing population and for cement industries.

 2. How does over grazing lead to desertification?

Answer: over grazing reduce the grass cover of land and expose the soil to the atmospheric air. The Soil dries up and its humus layer is lost which slowly changed grass land into desert.

Q. Give any two examples of the endemic flora of Pachmarhi Biosphere reserve.

Answer.  Sal and wild mango.

Q. Why is species of some animal become endangered?

Answer. Some species of animal become endangered, because of the disturbances in their natural habitat.

Q. Why migratory birds migrated from one place 'to another?

Answer. Migratory birds migrate to overcome climatic changes. For example, Surkhab migrated from Malaysia.

8th  Conservation of Plants and Animals Conservation of Plants and Animals        Download File
Check point[Formative Assessment]       Download File