Ifa rock had 80 radioactive atoms in it when it was formed and it now has 20 radioactive elements in it, how old is the rock?

All of the following are reasons why deserts extremely susceptible to wind erosion except a. they lack major root systems b. they contain thin, dry soil c. they have very few plants and trees d. they are extremely hot and lack water

In the scramble for africa, european powers drew boundaries and created states that benefitted the colonizers while ignoring the needs of the local populations. what effects did this policy have on the indigenous people following independence?

Which material is an aquifer layer most likely made of? soil clay solid granite cracked rocks