CBSE Class 12 Chemistry Sure Shot Questions (2). CBSE issues sample papers every year for students for class 12 board exams. Students should solve the CBSE issued sample papers to understand the pattern of the question paper which will come in class 12 board exams this year. The sample papers have been provided with marking scheme. It’s always recommended to practice as many CBSE sample papers as possible before the board examinations. Sample papers should be always practiced in examination condition at home or school and the student should show the answers to teachers for checking or compare with the answers provided. Students can download the sample papers in pdf format free and score better marks in examinations. Refer to other links too for latest sample papers.
1 MARK QUESTIONS
1. What are f-centres?
Ans- The free electron trapped in the anionic vacancies are called F-centres.
2. Name one solid in which both frenkel and schottky defects occur.
3. Why is vapour pressure of a solution of glucose in water lower than that of water?
Ans- This is due to decrease in escaping tendency of water molecules from the surface of solution as some of surface area is occupied by non- volatile solute particles such as glucose.
4. Why is glycol and water mixture used in a car radiators in cold countries?
Ans- Ethylene glycol lowers the freezing point of water, due to this, coolant in radiators will not freeze. Otherwise radiators will burst due to freezing of coolant.
5. What is the function of salt bridge?
Ans- It completes the circuit in the electrochemical cell and maintains electrical neutrality.
6. Write any two advantages of fuel cells.
Ans-(I) they do not cause any pollution.
(ii) They have high efficiency of 60-70%
7. What will be the effect of temperature on rate constant? Ans- Rate constant of the chemical reaction increase with the raise of temperature. It is observed that the rate constant of a reaction is nearly doubled when the temperature increased by 10°C.
8. Give an example of pseudo first order reaction.
Ans- acid catalyzed hydrolysis of an ester.
CH3COOC2H5 + H2O -- H+ -- > CH3COOH + C2H5OH
Rate = k3 [ CH3COOC2H5] [H2O]0
9. What do you mean by the term electrophoresis?
Ans. The movement of colloidal particles under an applied electric potential is called electrophoresis.
10. Define gangue.
Ans - The undesirable materials present in ore are known as gangue.
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