48.

Which chemical is not found in DNA nucleotides?

thymine

guanine

ribose

deoxyribose

Ribose. it's simple. you can immediately eliminate deoxyribose because DNA stands for deoxyribonucleic acid. and thymine and guanine are nitrogen bases which are found in DNA.

Ribose

Explanation:

DNA is a large molecule, a type of nucleic acid which store and act as a genetic material of the cell. DNA molecule is formed by the repeating monomer units called nucleotides.

Each nucleotide is made up of three subunits as:

1. 5-C sugar: De-oxyribose formed by the removal of oxygen group from 2' OH group of ribose. Ribose is the sugar molecule present in RNA nucleic acid.

2. Phosphate group (PO₄³⁻)

3. Nitrogenous bases: adenine, guanine, adenine and cytosine.

Thus, ribose is the correct answer.