The half life for the radioactive decay of potassium- to argon- is years. Suppose nuclear chemical analysis shows that there is of argon- for every of potassium- in a certain sample of rock. Calculate the age of the rock. Round your answer to significant digits.

i'm pretty sure it is letter c.) car

it’s previous models   because when i picked that son of a gun’s answer it was wrong look for previous models because they might make it a different letter  

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.