Haloalkanes & Haloarenes (XII Std) Important Questions from stereochemistry

Answers are given in the end.

Questions useful in Board Examination.

1. What is chirality?

2.Which compounds are chiral ?

3.What do you mean chiral centre?

4.What are the stereoisomers ?

5.What are the diastereomers ?

6.What is racemic mixture?

7.What is racemization ?

8.What do you mean retention of configuration ?

9.What do you mean by inversion of configuration ?

10.Whats the different between S_N1 and S_N2 Reaction mechanism?

Answers-

1.Chirality is the property of non-superimposability of an object over its mirror image.

2.The compound having chiral / asymmetric carbon is chiral.

3.The carbon bonded with four different atoms/ functional group is called chiral centre.

4.Enantiomers are the isomers which are non superimposable mirror images.

5.The stereoisomers which are not mirror images of each othr are called diastereomer.

6.The equimolar mixture of enentiomers which is optically inactive is called racemic mixture.

7.The reaction in which either of enantiomer is changed into racemic mixture ( Product ).If reactant is dextro rotatory or leavo rotatory than product is equimolar mixture of dextro and leavo rotatory.

8.The reaction in which product have same optical properties as reactant. If reactant is dextro rotatory than product is also dextro rotatory.

9.The reaction in which the optical property of reactant is inverted. If reactant is dextro rotatory than product will be leavo rotatory.

10. Difference between S_N1 and S_N2 Reaction mechanism

Point of difference	S_N1	S_N2
1.Type	Unimolecular	Bimolecular
2.Involvement of Transition State	No	Yes
3.Involvement of carbocation	Yes	No
4.Configuration of product or process	Racemic mixture	Inversion of configuration

Electrochemistry(XII Std) Important Questions Answers

Answers are given in the end

1.What is NFE/SHE ?

2.Explain the variation of conductivity with dilution. or How does conductivity varies with dilution ? Explain the reason for the variation ?

3.Explain the variation of molar conductivity of weak electrolyte with dilution. or How does conductivity of weak electrolyte varies with dilution ? Explain the reason for the variation ?

4.Explain the variation of molar conductivity of strong electrolyte with dilution. or How does conductivity of strong electrolyte varies with dilution ? Explain the reason for the variation ?

5.Explain Kohlrausch law

6.Calculate the Vont hoff’s factor for K₄[Fe{CN)₆] .

7.What is cell constant ?

8.Why can’t molar conductivity at infinite dilution of weak electrolyte be measured using graphical method ?

9.What are the secondary cells?

10. What are the fuel cells?

11.State advantages and disadvantages of fuel cells.

Answers- 1.The hydrogen electrode at 298 K with pressure of hydrogen is 1 bar and concentration of hydrogen is 1 M is called Standard Hydrogen Electrode / Normal Hydrogen Electrode. 2.Conductivity decrease with dilution because number of ions decreases per unit volume with dilution. ( Conductivity is the conductance of solution of unit volume/ one litre. 3. Molar conductivity of weak electrolyte increases with dilution due to increase in degree of dissociation. 4.Molar conductivity of strong electrolyte increases with dilution due to decrease in interionic attraction as interionic distance increase with dilution. 5.At infinite dilution molar conductivity of weak electrolyte is sum of contribution of molar conductivities of cations and anions which are independent of each other. 6. Von,t Hoff factor = 5/1 =5. 7. Cell constant is the ratio of length between vs area of electrode = L / A 8.Because line of graph never touch molar conductivity axes. 9.The cell which can be reuse again and again by charging. 10. The cell which generate energy from fuel without burning it , is called fuel cell. 11. Advantage of fuel cell-(1) It is pollution free (2) Continuous source of electricity (3) byproduct is water. Disadvantages of fuel cell- It is costly as catalysts is costly.