Answer:
chemical stability is important to consider in the comprehensive assessment of pharmaceutical properties, activity, and selectivity during drug discovery.
13. D
14. A
15. C
16. B
17. F
18. E
<h2>C</h2>
Explanation:
The atomic number of S is 
So,number of electrons in S is
The electronic configuration of S is 
The orbital electronic configuration of S is 
So,the number of orbitals involved is 9.
The number of C atoms in 0.524 moles of C is 3.15 atoms.
The number of 
molecules in 9.87 moles is 59.43 molecules.
The moles of Fe in 1.40 x 
atoms of Fe is 0.23 x 
The moles of 
in 2.30x
molecules of is 3.81.
<h3>What are moles?</h3>
A mole is defined as 6.02214076 × 
of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.
A. The number of C atoms in 0.524 mole of C:
6.02214076 × x 0.524 mole
3.155601758 atoms =3.155 atoms
B. The number of molecules in 9.87 moles of :
6.02214076 × x 9.87
59.4385293 molecules= 59.43 molecules
C. The moles of Fe in 1.40 x atoms of Fe:
1.40 x ÷ 6.02214076 ×
0.2324754694 x moles.
0.23 x moles.
D. The moles of in 2.30x molecules of :
2.30x ÷ 6.02214076 ×
3.819239854 moles=3.81 moles
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Answer: Adenine and guanine are the two purines and cytosine, thymine and uracil are the three pyrimidines. The main difference between purines and pyrimidines is that purines contain a sixmembered nitrogencontaining ring fused to an imidazole ring whereas pyrimidines contain only a sixmembered nitrogencontaining ring. They both are types or categories of nitrogen containing bases present in nuclei acids of DNA and RNA.
Purines are 2 Ring or Carbon Ring, Nitrogen containing bases. That consist of these 2 rings next placed next to each other. These examples include - Adenine and Guanine.
Pyrimidines are 1 or single Ring Nitrogen containing structures. There are 3 nitrogenous bases that are categorized as pyrimidines. Cytosine, Thymine, and Uracil.
