Ageologist finds an old rock and wants to determine its age using rubidium-strontium dating. this is possible because 87rb, which has a half-life of 4.75×1010 y, undergoes β − decay and becomes 87sr. the geologist determines that the ratio of 87sr to 87rb is 0.183. assuming there was no 87sr in the rock when it was formed, determine the age of the rock.

An alcohol thermometer makes use of alcohol's changing in order to measure temperature. as the temperature goes up, the alcohol contained in the thermometer increases in volume, filling more of the thermometer's tube.

The table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 10 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.

Adepositional also feature that forms where a stream enters a lake or an ocean is a