Deuterium is the isotope of hydrogen of mass number 2, with a proton and a neutron in its nucleus. The chemistry of deuterium is nearly identical to the chemistry of hydrogen, except that C-D bond is slightly (5.0 "KJ" //"mole") stonger than the C-H bond. Reaction rates tend to be slower if a C-D bond as opposed to a C-H bond is broken in a rate limiting step. This effect on the rate is called a kinetic isotope effect.

Deuterium is the isotope of hydrogen of mass number 2, with a proton a

1.	Deuterium is the isotope of hydrogen of mass number 2, with a proton and a neutron in its nucleus. The chemistry of deuterium is nearly identical to the chemistry of hydrogen, except that C-D bond is slightly (5.0 "KJ" //"mole") stonger than the C-H bond. Reaction rates tend to be slower if a C-D bond as opposed to a C-H bond is broken in a rate limiting step. This effect on the rate is called a kinetic isotope effect.
Answer» `(K_(H))/(K_(D))=1` `(K_(H))/(K_(D))~~4` `(K_(D))/(K_(H))~~4` `(K_(D))/(K_(H))~~2` Solution :As deprotonation STEP in case of IODINATION is rate determinining.