Final answer:
The reactive metal in question is calcium (Ca), which is essential for bone strength and is found in dairy products.
Step-by-step explanation:
The reactive metal whose compounds make up limestones, chalk, cement, and the bones and teeth of animals, and is also a good nutritional source from milk, is calcium (Ca). Calcium is needed for bone strength, neutralizing acidity in the digestive tract, and is vital for nerve and cell membrane functions. Dairy products are indeed good sources of calcium, which is essential for the human body. Other minerals, such as magnesium and phosphorus, also play significant roles in bone health and other physiological processes.