About how many cells are made of water

Which plains area lies in both the united states and canada? altiplano central canadian shield coastal plains great plains

When a human or animal consumes food, the carbon in that food is most likely to be converted into which of the following elements? a. carbon remains carbon b. nitrogen c. oxygen d. hydrogen

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?