2. in the sn1 mechanism, the second step is attack of the nucleophile, so increasing the nucleophile concentration should speed up this step. why, then, do we say that the rate of an sn1 reaction does not depend on the concentration of the nucleophile?

The rate of reaction depends on the rate determining step of a nonelementary reaction

Explanation:

A non elementary reaction is a reaction that proceeds in a sequence of steps. One of the steps is usually the slowest step in the reaction sequence. This slowest step is called the rate determining step. In an SN1 reaction, the rate determining step is the formation of the carbocation, the concentration of the carbocation affects the rate of reaction because it is involved in the rate determining step. The attack of the nucleophile is a fast step and does not affect the rate of reaction.

hey, i believe your answer would be d. sugar ribose and the base uracil. i believe this is the answer, because rna consists of sugar ribose, adenine, guanine, cytosine, and uracil.

your first option is incorrect, because that's dna. where it consists of sugar deoxyribose, adenine, guanine, cytosine and thymine.

your second option is also incorrect, this is because sugar deoxyribose is in dna, and uracil is in rna. these two do not make sense together.

your third option being incorrect, because sugar ribose is in rna, but not the base of thymine. rna consists of uracil, not thymine.

lastly your fourth option being correct! this answer is correct, because both sugar ribose, and the base uracil are in rna! ~

answer is d. sugar ribose and the base uracil.

straight or amphibians are homeothermic to thermal