Final answer:
Barium (Ba) is highly reactive, especially at room temperature. It reacts vigorously with water and air, forming hydrogen and the metal hydroxide. This reactivity makes D. It is very reactive, the correct answer.
Step-by-step explanation:
The student's question, 'Which is a property of barium (Ba)?' refers to characteristic features of chemical elements, particularly barium. Among the options provided,
- D. It is very reactive. is the correct choice.
Barium is an alkaline earth metal, and like its counterparts such as magnesium, calcium, and strontium, it reacts with water and air. At room temperature, barium demonstrates a vigorous reaction with water to form hydrogen and barium hydroxide. This reactivity is due to barium being a good reducing agent, suggesting that it is easily oxidized. Barium reacts with both acids and nonmetals to form ionic compounds. Therefore, the property of barium that correctly answers the question is its high reactivity.