Potassium-40 (k-40) decays into argon-40 (ar-40). which of the following are true statements? select all that apply. a. k-40 is the parent, and ar-40 is the daughter. b. ar-40 is the parent, and k-40 is the daughter. c. a rock sample containing a relatively small amount of ar-40 is old. d. a rock sample containing a relatively small amount of ar-40 is young.

The correct answers are options A. "K-40 is the parent, and Ar-40 is the daughter" and D. "A rock sample containing a relatively small amount of Ar-40 is young".

Explanation:

Potassium-40 (K-40) is a radioactive isotope that decays into argon-40 (Ar-40) with a really long half-life of 1.251 billion years. Since K-40 is the one that produces Ar-40, K-40 is considered the parent isotope and Ar-40 is considered the daughter isotope. This phenomenon is used to date rocks, known as the potassium–argon dating approach. A rock sample containing a relatively small amount of Ar-40 is young, because K-40 takes a long time to decay and the more Ar-40 is in the rock the more time has passed since the rock was created.

English-The outer surface of bone, except in regions covered with articular cartilage, is covered with a fibrous membrane called the periosteum.

Spanish-La superficie externa del hueso, excepto en las regiones cubiertas con cartílago articular, está cubierta por una membrana fibrosa llamada periostio.

Explanation: