Element P is a Group 1 metal whose ion has the maximum magnitude of hydration enthalpy in its group. Element Q is a Group 2 metal whose ion has the maximum magnitude of hydration enthalpy in its group. Element P exhibits a diagonal relationship with an element R . The identities of elements R and Q , respectively, are

Step-by-step solution

The magnitude of hydration enthalpy is inversely proportional to the ionic size. In Group 1 , the Li ⁺ ion is the smallest, so Lithium ( Li ) has the maximum magnitude of hydration enthalpy. Thus, element P is Li . In Group 2 , the Be ²⁺ ion is the smallest, so Beryllium ( Be ) has the maximum magnitude of hydration enthalpy. Thus, element Q is Be . Lithium ( P ) exhibits a diagonal relationship with Magnesium ( Mg ) in Group 2 . Therefore, element R is Mg . The identities of elements R and Q , respectively, are Mg