Final answer:
Sodium (Na) is the soft metal among the given elements, being soft enough to cut with a knife. Potassium (K) has the smallest ionization energy. Selenium (Se) is a nonmetal, Magnesium (Mg) is an alkaline earth metal, and Germanium (Ge) is a metalloid.
Step-by-step explanation:
The question asks to identify which among the given elements – Al (aluminum), Au (gold), Br (bromine), Ca (calcium), Cs (cesium), F (fluorine), H (hydrogen), He (helium), Hg (mercury), I (iodine), K (potassium), Mg (magnesium), Na (sodium), O (oxygen), P (phosphorus), S (sulfur), and Si (silicon) – is a soft metal. The answer is Na, which is sodium. Sodium is an alkali metal and is known for being soft and easily cut with a knife.
In terms of ionization energy, potassium (K) would have the smallest ionization energy among K, P (phosphorus), S (sulfur), and Ca (calcium) because it is in the first group of the periodic table and loses its electron more easily than the others.
When classifying elements based on the periodic table:
- Se (selenium) is a nonmetal.
- Mg (magnesium) is an alkaline earth metal.
- Ge (germanium) is a metalloid.