What is the half-life of a radioisotope if a 20 g sample becomes 5 g after 2 days?

Which property of a rock remains unchanged by mechanical weathering? a. total surface area b. size and shape c. mineral composition d. sharpness

What is calcium oxide+diphosphorus pentoxide--> calcium phosphate balanced

Four statements about the development of the atomic model are shown below. a: electrons have wavelike properties. b: atoms have small, negatively charged particles. c. the center of an atom is a small, dense nucleus. d: atoms are hard, indivisible spheres. which order of statements represents the historical development of the atomic model? c-d-a-b c-d-b-a d— в-а — с d-b-c-a