12th Chemistry (Term-I) 2020-21

12th Chemistry (Term-I) 2020-21*Required

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12th Chemistry (Term-I) 2020-21 https://docs.google.com/forms/d/e/1FAIpQLSccJwDtV9...

1 of 11 13/06/21, 14:07

Option 1 Option 2

Option 3 Option 4

(a) mole fraction

(b) molar mass

(c) boiling point of liquid

(d) molar mass of solvent

1. Which of the following is incorrect for an ideal solution? *

*


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True

False

Option 1 Option 2

Option 3 Option 4

3. Water is non-volatile solvent. *

4. Which of the following statement is correct? *


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(a) Assertion and reason both are correct statements and reason is correctexplanation for assertion.

(b) Assertion and reason both are correct statements but reason is not correctexplanation for assertion.

(c) Assertion is correct statement but reason is wrong statement.

(d) Assertion is wrong statement but reason is correct statement.

5. *In the following questions a statement of assertion followed by a statement of reason is given. Choosethe correct answer out of the following choices


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Option 1 Option 2

option 3 (C) Cu is reducing agent Option 4

True

False

*

*


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(a) Both assertion and reason are correct and the reason is correct explanation ofassertion.

(b) Both assertion and reason are correct but reason does not explain assertion.

(c) Assertion is correct but reason is incorrect.

(d) Both assertion and reason are incorrect.

(e) Assertion is incorrect but reason is correct.

(a) 693 min

(b) 6.93 min

(c) 0.693 min

(d) 6930 min

8. Assertion: Order and molecularity are same. Reason: Order is determinedexperimentally and molecularity is the sum of the stoichiometric coefficient ofrate determining elementary step. *In the following questions a statement of assertion followed by a statement of reason is given. Choosethe correct answer out of the following choices

9. A first order reaction is 50% complete in 69.3 minutes. Time required for99.9% completion of this reaction is *


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Option 1 Option 2

Option 3 None of these

True

False

True

False

10. Which of the following graphs is correct for a first order reaction? *

11. Photosynthesis is zero order reaction. *

12. Enzyme work at specific pH and optimum temperature *


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Option 1 Option 2

Option 3 Option 4

(a) Among halogens, radius ratio between iodine and fluorine is maximum.

(b) Leaving F—F bond, all halogens have weaker X—X bond than X—X’ bond ininterhalogens.

(c) Among interhalogen compounds maximum number of atoms are present iniodine fluoride.

(d) Interhalogen compounds are more reactive than halogen compounds

13. Which one of the following order is correct for the bond dissociationenthalpy of halogen molecule? *

14. Which of the following statements are incorrect? *


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True

False

Option 1 Option 2

Option 3 Option 4

*

16. Which of the following is affected by catalyst? *


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Option 1 Option 2

Option 3(d) All are correct of different rangesof pressure

(a) absorption

(b) adsorption

(c) both absorption and adsorption

(d) desorption

17. According to Freundlich adsorption isotherm, which of the following iscorrect? *

18. The term ‘sorption’ stands for ____________. *


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(a) Lyophobic sol is protected.

(b) Lyophilic sol is protected.

(c) Film of lyophobic sol is formed over lyophilic sol

(d) none of these

(a) It acts as bleaching agent in moist conditions.

(b) It’s molecule has bend structure.

(c) It’s dilute solution is used as disinfectant.

(d) It has two lone pairs in its geometry.

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19. What happens when a lyophilic sol is added to a lyophobic sol.? *

20. *

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11 of 11 13/06/21, 14:07

Bhagwan Mahaveer Public Sr. Sec. School, Banga Exam: Term 1- (Sep, 2020)

Subject : Chemistry

Class : 12th M.M: 50 Section-B

Two marks Questions : (2x7=14)

1) State Raoult’s Law for a solution containing volatile components. How does Raoult’s law

become a special case of Henry’s Law? (02)

2) Following reactions occur at cathode during electrolysis of aqueous sodium chloride solution: (02)

On the basis of their standard electrode potential (E°) values, which reaction is feasible at the cathode and why?

3) What do you understand by the rate law and rate constant of a reaction? Identify the order of a reaction if the units of its rate constant are : (02) (i) L–1 mol s–1 (ii) L mol–1 s–1

4) Write the difference between physisorption and chemisorption with respect to the following:

(i) Specificity (ii) Temperature dependence (iii) Reversibility and (iv) Enthalpy change.(02)

5) Give two chemical methods for the preparation of colloids. (02)

6) What is Ziegler Natta catalyst? Give its use. (02)

7) Assign an appropriate reason for each of the following statements: (02)

(i) More metal fluorides are ionic in nature than metal chlorides.

(ii) SCl6 is not known but SF6 is known. Or

Give the physical properties of Ozone.

Three marks questions : (3x7=21)

8) Calculate the mass of compound (molar mass = 256 g mol–1) to be dissolved in 75 g of

benzene to lower its freezing point by 0.48 K (Kf = 5.12 K kg mol–1). (03)

9) What is the molality of ammonia in a solution containing 0.85 g of NH3 in 100 mL of a liquid

of density 0.85 g cm–3? (03)

10) Calculate E°cell and ∆rG° for the following reaction at 25°C. (03)

A2+(aq) + B+(aq) → A3+(aq) + B(s)

[Given KC = 1010, 1F = 96500 C, R = 8.314 JK–1 mol–1]

11) For the reaction (03)

2NO(g) + Cl2(g) → 2NOCl(g),

the following data were collected. All the measurements were taken at 263 K:

(a) Write the expression for rate law.

(b) Calculate the value of rate constant and specify its units.

(c) What is the initial rate of disappearance of Cl2 in experiment no. 4?

12) Write three features of chemisorptions which are not found in physisorptions. Illustrate your

answer with suitable examples. (03)

13) Give reasons for the following observations: (03)

(i) Leather gets hardened after tanning.

(ii) Lyophilic sol is more stable than lyophobic sol.

(iii) It is necessary to remove CO when ammonia is prepared by Haber’s process.

14) (a) What are micelles? How do they differ from ordinary colloidal particles? Give two

examples of micelles forming substances. (03)

(b) State Hardy–Schulze rule.

(c) State the principle of electro dialysis. Or

a) Why do doctors advice Gargles by saline water in case of sore throat. (1 ½ ) b) What is the semi-permeable membrane? (1 ½ )

Five marks Questions : (5x3=15)

15) Complete the following chemical equations: (03)

b )Arrange the following in the order of property indicated against each set: (02)

(i) HF, HCl, HBr, HI – increasing bond dissociation enthalpy.

(ii) H2O, H2S, H2Se, H2Te – increasing acidic character

Or

What is the basic principal upon which galvanic cell do work. Explain the construction work

with chemical reactions.

16 (a) Explain the following: (05)

(i) Henry’s law about dissolution of a gas in a liquid.

(ii) Boiling point elevation constant for a solvent.

(b) A solution of glycerol (C3H8O3) in water was prepared by dissolving some glycerol in

500 g of water. This solution has a boiling point of 100.42 °C. What mass of glycerol was

dissolved to make this solution? (Kb for water = 0.512 K kg mol–1)

Or

(a) Define the following terms:

(i) Limiting molar conductivity (ii) Fuel cell

(b) Resistance of a conductivity cell filled with 0.1 mol L–1KCl solution is 100 Ω. If the

resistance of the same cell when filled with 0.02 mol L–1KCl solution is 520 Ω, calculate

the conductivity and molar conductivity of 0.02 mol L–1KCl solution. The conductivity of

0.1 mol L–1KCl solution is 1.29 × 10–2 Ω–1 cm–1.

17 (a) For a chemical reaction R → P, the variation in the concentration, ln[R] vs. time (s)

plot is given as shown in figure : (05)

(i) Predict the order of the reaction. (ii) What is the slope of the curve?

(iii) Write the unit of rate constant for this reaction. (b) Show that the time required for 99% completion is double of the time required

for the completion of 90% reaction.

Or

(a) Using VSEPR theory, predict the possible structures of the following:

(i) XeF2 (ii) XeO3.

(b) (i) Why is SF6 Kinetically inert?

(ii) Why is F2 more reactive than Cl2inspite of chlorine has higher electron gain enthalpy

than fluorine?

(iii) Why is HF weaker acid than HCl?

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12th Chemistry (Term-I) 2020-21