CBSE Class 12 VBQs for chemistry Set A

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CBSE Class 12 VBQs for chemistry Set A  Based on CBSE and NCERT guidelines. Value based questions are now being given in exams to promote morals and values in students, Students should read and understand the following VBQs to get better understanding and score good marks in exams

Value Based Questions Chemistry–XII

1. Rahul and Satya decided to commence a partnership to export ready made garments. Their capital contributions were mutually agreed to be  Rs 3,00,000 and Rs. 2,00,000 respectively. The other clauses of the partnership deed were as follows:

After reading the above passage, answer the following questions.

(i) Why did the sales boy refuse to put the sweet box in a polyethene bag?

(ii) As a student of chemistry, why would you advocate the use of paper bags instead of polyethene bags? Which values are promoted through the use of paper bag?

(iii) Suggest two activities to promote these values.

Ans.(i) Polyethene is banned because of being non-degradable.

(ii) Use of polyethene bags results in pollution as polyethene is non-biodegradable.

Value: Reducing environmental pollution, concern for environmental protection.

(iii) Organizing mass campaigns for spreading awareness/Use of mass media to educate people.

2. In thermal power stations, coal is burnt to produce steam for generation of electricity. The smoke produced is passed through electrostatic precipitators.

Answer the following questions based on the above information:

(i) Why is the smoke passed through electrostatic precipitators in thermal power stations? Which property of colloidal solution is used in an electrostatic precipitator?

(ii) How does coal ash affect environment? Suggest a method to use coal ash.

(iii) Which value is promoted through the use of electrostatic precipitator?

(iv) Suggest one activity to inculcate this value in students.

Ans.(i) To prevent the passage of particulates in atmosphere. Electrophoresis.

(ii) Coal contains sulphur, arsenic, lead. Thus, coal ash contaminates air and water. Coal ash can be used to form bricks for the construction of buildings.

(iii) Value: Reducing air and water pollution/Environmental concern.

(iv) Organizing Debate on related topic/Assigning projects.

3. There is a poster with the slogan “Hum do Hamare do” pasted on a wall.

Answer the following questions based on above slogan:

(i) What message does above slogan convey?

(ii) Use of condoms and anti-fertility drugs help in avoiding pregnancy. Name one anti-fertility drug and one polymer used in the manufacture of condoms.

(iii) Which value is promoted through the poster? What are the disadvantages and challenges related to violation of this value?

Ans. (i) Family planning

(ii) Norethindrone/Ethynylestradiol (Novestrol). Polyurethane/polyisoprene.

(iii) Population control. The increased population has caused many social problems such as shortage of food, environment issues and unemployment, etc.

4. An organic compound X which is manufactured by heating a mixture of chloral and chlorobenzene in the presence of concentrated H2So4 is used as an insecticide. The use of compound X is banned in many countries. The compound is very effective against mosquitoes which spread malaria.

Answer the following questions based on above Information:

(i) Name the compound X. Give its structural formula and IUPAC name.

(ii) Why the use of compound X is banned in many countries? Should we also advocate the ban of this compound though it is banned in many countries?

(iii) Which value is reflected in its ban? Should our country exactly the same rules and regulations in such matters as those being followed in other countries?

Ans. (i) DDT 


 IUPAC  name: 2, 2-Bis (4-chlorophenyl)-1, 1, 1-trichloroethane.

(ii) It should be banned. It has its harmful effects on microorganisms and vegetation.

(iii) Values: Reducing environmental pollution/Environmental protection. Every matter should be considered at its own merit through proper debate and scientific reasoning.

5. A junior scientist in a leading dental cream manufacturing company discovers that the addition of a certain element to a dental cream can bring about a significant improvement in the quality of product in controlling tooth diseases. However, she also discovers that the same element can also result in one in a million cases of user, getting a deadly disease. The scientist reports her results in full in the Board’s meeting. Assuming that you are the CEO of the company,

Answer the following questions on the basis of above information:

(i) Should the company go ahead with manufacturing the product without bothering or sharing the ill effects of the product? Give reasons for your answer.

(ii) How will you respond to a suggestion from a colleague that the company should do more research for reducing the ill effects before manufacturing the product?

(iii) How will you respond to a suggestion from another colleague that the company should altogether ban the idea of manufacturing this product?

(iv)Which values are promoted through this anecdote?

Ans. (i) No, the ill effects of the product should be avoided at all costs even if it is on one in a million cases.

(ii) Yes. The company should take initiatives for continue research to minimize ill effects.

(iii) No. Efforts should be made to remove the ill effects of the product along with improvement in the quality.

(iv) Intellectual honesty —Professional ethics

6. You have gone to a chemist shop to get medicines. A person is pleading with the shopkeeper to get sleeping pills without doctor’s prescription. The chemist is reluctant to give him sleeping pills without doctor’s prescription stating that the pills can be misused and have adverse ill effects.

Answer the following questions based on the above information:

(i) Should the shopkeeper give sleeping pills to the customer even when he does not having doctor’s prescription? Justify your answer.

(ii) Is there any alternative approach/action the shopkeeper can take to help the customer without giving him the pills? Which values are reflected in this alternative approach?

Ans. (i) No. Such medicines should not be given without proper prescription or verification because these medicines can be used in many ways. An overdose of these pills can even result in death of a person.

(ii) Alternatives:

(a) Directly taking to doctor and seeking his/her advice.

Value: Professional ethics

(b) Seeking more information about patient’s past history to know the reasons for sleeplessness and advising the customer to consult another doctor before taking sleeping pills.

Value: Professional commitment

7. A poster suggests following lifestyle actions on the part of families/individuals:

(a) Use soaps made of vegetable oils instead of using synthetic detergents.

(b) Use H2O for bleaching purpose instead of using chlorine based bleaching agents.

(c) Use plastic cans for neatly storing substances.

(d) Use bicycle for travelling small distances than petrol or diesel vehicles.

Answer the following questions based on above information:

(i) Which of the above lifestyle suggestion promote green chemistry?

(ii) Which environmental values are promoted through these lifestyles?

(iii) Suggest two additional lifestyles actions for promotion of green chemistry.

Ans. (i) All a, b, and c, promote green chemistry.

(ii) Reducing environmental pollution.

(iii) Avoiding excessive storage in refrigerators, minimizing use of preservatives or using organic manure for gardening.

8. You stop at a red signal while travelling in your own car. Your friend suggests that you should stop the car engine in order to minimize harmful emissions and save fuel. You do not stop the car engine arguing that you have to stop only for a sort while. You also argue that the nearby green plants will prevent air pollution, if any.

Answer the following questions based on above information:

(i) Which environmental values are being violated by you by not agreeing to your friend’s suggestions?

(ii) Suppose the government introduces rules for the vehicle owners to compulsorily stop the vehicle engine whenever it stops at the red signal. Will you support Government’s rule or consider it a violation of human driving rights.

(iii) How will you respond to your friend’s observation that you are damaging nearby green plants also by not switching off the car engine?

Ans. (i) Environmental protection concern for life.

(ii) Support Government’s move. The new move is for the common good.

(iii) I shall agree with my friend’s viewpoint.

9. Fermentation of sugars gives a mixture containing an alcohol, A, and water. The alcohol-water mixture on fractional distillation gives an azeotrophic mixture. The azeotrope has composition 95.6% alcohol and 4.4% water by mass. The mixture is commonly called rectified spirit. To refrain people from drinking rectified spirit, the industrial alcohol is denatured. Some countries now use the alcohol A as an additive in gasoline since it is cleaner fuel.

After reading the above passage, answer the following questions.

(i) Identify alcohol A. Write reactions involved in the fermentation of a sugar.

(ii) What is denatured alcohol? Why industrial alcohol is denatured?

(iii) Would you support the use of alcohol ‘A’ as an additive in gasoline in India although it may result in decrease in the production of sugar?

(iv) What are the values associated with your decision?

Ans. (i) A = Ethanol.  


(ii) Industrial alcohol is made unfit for drinking by adding in it some copper sulphate (to give it colour) and pyridine (a foul smelling liquid) called denatured alcohol. Ethanol is an excellent solvent and large quantities of it are need for various chemical industries. In order to supply cheaper ethanol to industries and to refrain people from drinking, it is denatured.

(iii) Yes. Gasoline need of our country is mainly met by importing it. Import of gasoline increases our fiscal deficit. To meet the energy requirements and to reduce oil pool deficit of country one should support use of ethanol as an additive in gasoline. But it must be regulated by Government.

(iv) Values—Concern for energy crisis —Concern for economy of country.

10. Anil and his neighbour Sunil have got their garden fenced with iron rods. Anil saw the next day that Sunil was painting the iron fence. Sunil suggested Anil to do the same to increase the longevity of the iron rods by preventing corrosion. Anil argues that it is a waste of time and his iron rods are quite strong.

After reading the above passage, Answer the following questions.

(i) Whose opinion is correct according to you? What values are promoted here?

(ii) Why do car owners living near the sea wash their cars regularly?

(iii) Are there any other ways to prevent corrosion other than painting?

Ans. (i) According to me Sunil is correct because painting cuts off the contact of air and moisture with iron. Both air and moisture are required for corrosion to occur.


(ii) Salt speeds up the rusting of iron. The metal in car would rust faster by the deposition of salt on them if not washed regularly.

(iii) Other methods are: oiling/greasing, covering with plastic, galvanizing.


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