Answer : A nucleotide is composed of a phosphate group and a nitrogen-containing base.
Explanation :
Nucleotide : It is a building block of nucleic acids or we can say that it is building block of DNA and RNA.
It is composed of three sub-unit molecules which are a nitrogenous base, a five-carbon sugar and one phosphate group.
Nucleotide forms covalent bonds with other nucleotide for the formation of the nucleic acid strand.
Hence, a nucleotide is composed of a phosphate group and a nitrogen-containing base.
42.4 ml is the volume in milliliters of the lead ball if a lead ball is added to a graduated cylinder containing 50.6 ml of water.
<h3>What is a graduated cylinder?</h3>
A tall narrow container with a volume scale is used especially for measuring liquids.
The graduated cylinder contains water
mL is a volume unit.
Water volume = 50.6 ml
The lead ball caused an increase in volume from 50.6 ml to 93.0 mL.
The new volume is the lead ball volume plus the original water volume :
Final volume = Vlead ball+ Water original volume



Hence, 42.4 ml is the volume in milliliters of the lead ball.
Learn more about the graduated cylinder here:
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Answer:
lithium 3
Explanation:
This is because lithium has three protons