Apyrimidine is joined covalently to the pentose sugar through the: a) n-1 of the base to the 1 carbon of the pentose. b) n-9 of the base to the 1 carbon of the pentose.

A) N-1 of the base to the 1 carbon of the pentose.

Explanation:

Nucleoside is the combination of both the sugar molecule and the base attached to it.

There are two kinds of bases, which are:- purine (contains Adenine and Guanine) and pyrimidine (contains Cytosine, Thymine and Uracil). The base is pyrimidine, then the N-1 of the nitrogenous base is attached to C-1' of the parent chain. While if the base is purine, then the N-9 of the nitrogenous base is attached to C-1' of the parent chain.

Hence, The answer is:- N-1 of the base to the 1 carbon of the pentose.

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"