A collector of rare items is negotiating with a museum. He wants to sell a spear he claims to have been used to kill a mammoth over 11,000 years ago. A spear that size would have started with around 4g of
Carbon-14, and the museum tests show it now contains around 2g. How many half-lives have passed since the spear was carved?

I'm not sure if you maybe forgot to add in some information but I can give you the equation you will need to solve this..! (just without the bit of infomration you might need)

In this case you'll be solving for t and I can help you with your first step, you'll divide 2 by 4, getting you to:

measure their densities same density, same sub

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.