Answer: Potassium-40 decays into argon gas over time.
Explanation: Potassium-argon dating is a dating method used to determine the age of sedimentary rocks by comparing the proportion of K-40 to Ar-40 in a sample of rock, and knowing the decay rate of K-40.
Potassium-40 undergoes decay following first order kinetics as given below:

It is necessary because Oxygen demands need to be reduced. This may require more aggressive support
including the use of continuous positive airway pressure (CPAP) or mechanical
ventilation. Newborns born to drug-addicted mothers exhibit hyperirritability,
exaggerated reflexes, and transient tachypnea.
Answer:
The correct answer will be option-B (purine).
Explanation:
Nucleic acid structure is made up of monomer unit called nucleotide. Each nucleotide is composed of a five-carbon sugar, a phosphate group and five types of nitrogenous bases.
The nitrogenous bases are categorized in two forms the purines (adenine and guanine ) and the pyrimidines (cytosine, thymine and uracil). The "purines" contain double rings in their structure due to which they appear larger in size than pyrimidines which are made up of single rings.
Thus, Option-B is the correct answer.
Answer:
Topoisomerase
Explanation:
Topoisomerases are enzymes that produce changes in the topology of the DNA during replication, transcription, traduction, or reparation processes. They can cut one or both strands and in order to relieve torsional stresses in the supercoiled structure of DNA. With this, they help to maintain the chromosome's integrity. There are two types of topoisomerases: topoisomerase I (it cuts only one strand of DNA) and topoisomerase II (it is able to cut both strands of DNA).
Answer: DNA ligase.
Explanation:
Polymerase chain reaction is a technique used in molecular biology by scientists to make several copies of a DNA sample which enable them to take a smaller portions of it and expand it for more detailed study.
PCR mixture is premixed and contain thermostable DNA polymerase, oligonucleotides primer, four deoxynucleodide triphosphates, Magnesium chlorides, a propietary buffer.