Final answer:
The chemical properties of elements are most similar within the same group of the periodic table. Nitrogen and phosphorus are both in group 15, making their properties the most similar compared to the other options provided.
Step-by-step explanation:
In which pair of elements are the chemical properties of the elements most similar? The given options are:
- Sodium and chlorine
- Nitrogen and phosphorus
- Boron and oxygen
The chemical properties of elements are most similar within the same group of the periodic table because they have the same number of valence electrons, which determine reactivity and bonding behavior. Nitrogen (N) and phosphorus (P) both belong to group 15 of the periodic table, also known as the pnictogens or the nitrogen group. Therefore, they share similar chemical properties such as forming three covalent bonds, having a -3 oxidation state in compounds, and being able to form similar types of molecules. In contrast, sodium (a group 1 alkali metal) and chlorine (a group 17 halogen), and boron (a group 13 element) and oxygen (a group 16 element) are not in the same group and thus have dissimilar chemical properties.
Answer: b) Nitrogen and phosphorus