In which time period were the first animals that could live both water and land

The p sub shell can hold up to 8 electrons in an atom. true or false?

Calculate - analysis of compound composed of iron and oxygen yields 174.86 of fe and 75.14g of o. what is the empirical formula for this compound?

Aradio signal from a gps satellite take only about 0.067 seconds to reach a gps reciever. if the speed of light is about 300,000km/s, then approximately how far away is the reciever from from the satellite?