physical and chemical properties

In the modern periodic table, the element calcium (atomic number = 20) is surrounded by elements with atomic numbers 12, 19, 21 and 38. Which of these elements has physical and chemical properties resembling those of calcium and why?

Which physical or chemical properties affect thedecay rate or half-life ofa radioactive isotope ?

Physical & chemical properties of Aryl Halides

Preparation of organic halides | Physical & chemical properties of Alkyl Halides

List in tabular form three physical and two chemical properties on the basis of which ethanol and ethanoic acid can be differentiated.