What property of radioactive elements makes them useful for determining absolute age

Radiogenic isotopes.

Explanation:

Dating is a process by which archaeologists get to know the absolute or relative age of a past objects. Absolute dating deals with the process of determining  the absolute age of the  element.  During dating of objects, or during the radiometric dating if we know the half-life of the element, it will be easy to know the age of that object by determining the decay rate of the isotopes.  

a

explanation:

many plants naturally reproduce this way, but it can also be induced artificially. horticulturalists have developed asexual propagation techniques that use vegetative plant parts to replicate plants. success rates and difficulty of propagation vary greatly. monocotyledons typically lack a vascular cambium and therefore are harder to propagate.