Question

Elements are organized on the periodic table based on their properties. Which statement correctly predicts and explains the chemical reactivity of two different metals?

Barium (Ba) is less reactive than calcium (Ca) because the valence electrons in calcium atoms are farther from the nuclei and harder to remove.
Strontium (Sr) is more reactive than magnesium (Mg) because the valence electrons in strontium atoms are farther from the nuclei and harder to remove.
Rubidium (Rb) is more reactive than sodium (Na) because the valence electrons in sodium atoms are closer to the nuclei and easier to remove.
Lithium (Li) is less reactive than potassium (K) because the valence electrons in lithium atoms are closer to the nuclei and harder to remove.

Answer 1

Correct answer: "Lithium (Li) is less reactive than potassium (K) because the valence electrons in lithium atoms are closer to the nuclei and harder to remove."

Explanation: For metals in the same group, reactivity increases down the group because the outermost electrons are farther from the nucleus and more shielded, so they are easier to remove. Potassium's valence electron is farther from the nucleus than lithium's, so K is more reactive and Li is less reactive. The other statements give the wrong trend or the wrong reason.