What are the DNA base pairing rules? Does the image above follow the rules?

Select all that apply genes are specific nucleotide sequences occur in numbers that are the same as the number of chromosomes are located in a specific place on a chromosome determine the traits of an organism are units of rna

Which of the following is a period in the paleozoic era? devonian cambrian permian all of the above

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?