Mixture. Mixtures can be separated into their component parts, while substances are chemically bonded atoms that can't be separated by physical means.
Copper nitrate
Copper nitrate is the oxidizing agent as it gets reduced from +2 to 0 oxidization State and oxidize Fe from 0 to +2 state.
Answer;
D. carbon-12 atom
Explanation;
-One atomic mass unit is the mass that is exactly equal to one-twelfth the mass of one carbon-12 atom. Therefore, the mass of carbon-12 is 12 amu and this provides the standard that is used in measuring the atomic mass of all other elements.
-The atomic mass of carbon is 12.01 and not 12.00 in the periodic table.
-Due to the fact that there are more than one element for most naturally occurring elements, the average mass of the naturally occurring mixture of isotopes is taken while determining the atomic mass of an element.
Answer: Natural selection.
Explanation:
The natural selection is the process by which the organism that best suits the characters will survive and the organism which cannot adapt the changes will die.
The predators feed on their prey and the organism which hides easily in the environment due to its color is safe and the animals that cannot camouflage will die.
This is natural selection that more favored character is carried out over generations and other that cannot survive die.