Final answer:
In a period, the alkali metals have the largest atomic radii and the lowest first ionization energies, which is attributed to their position in the periodic table and the ease of removing their single valence electron. The correct answer to the question is (a) Largest, lowest.
Step-by-step explanation:
In a period, the alkali metals have the largest atomic radii and the lowest first ionization energies. The statement holds because in the periodic table, as we move from left to right within a period, the atomic radius generally decreases while the ionization energy increases. This trend is due to the increasing nuclear charge, which attracts the electrons more strongly and makes it harder to remove them. However, alkali metals, located in the first group of the periodic table, have a single electron in their outermost shell. This makes the electron relatively easy to remove, leading to their characteristic large atomic radii and low ionization energies.
To answer the question: In a period, the alkali metals have the largest atomic radii and the lowest first ionization energies. Therefore, the correct answer is (a) Largest, lowest.