A the concentration gradient!
Answer: Literally no clue
Explanation: Give me the points queen :)
I am thinking D. But I am not sure that it is the answer.
To perform this test to check if gold is real, make a light, tiny scratch on the item using a small nail file. Choose a spot that is not noticeable if possible. Use a dropper to apply a small drop of nitric acid to the scratch. If there is no reaction, then the piece is probably made from real gold.
Despite their frequency in the intertidal zone, in tide pools, sea urchins can be found at many different depths and in any habitats. They can also be found in nearly any ocean temperature. Sea urchins inhabit the polar seas as well as the warm tropics.
