Which is smaller in each of the following. l l^. and Ca or Ca^+2

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?

Match the mixture with the substance// i really need on this guys (it’s a pic btw)

Ab c or d ? i’m not sure what the answer is