Markownikoff rule is w.r.t. to electrophilic substitution whereas

SAYTZEFF RULE is w.r.t. to elimination

+ and - refer to the sign of rotation d- or l-

 

D- and L- refer to the position(left or right) of -OH or -NH2 on the last chiral carbon.

There are compounds which are D(-) and those which are L(+)

200% correct koni. U r really good.

 

By the way sandeep I am right only the 4th question is 1/e.

It is the mode of attack that determines the stereospecificity. In the reaction of singlet carbene the pi orbitals are involved in bonding with the p-orbital which contains the lone pair and it forms a complex and which does not disturb the stereochemistry of the original comound. Whereas in the triplet reaction since it has 1 electron each in 2 orbitals if first attacks the first carbon creating a carbocation which then destroys the stereospecificity.

 

Example:

cis-2-butene + :CH2(singlet) --> cis-1,2-dimethyl cyclopropane

cis-2-butene + :CH2(triplet) ---> cis- + trans-(50% and 50%).

Sorry sandeep ur answer is 200% wrong.

Try using the concept of limit of sum.