Answer:
a pure substance consists only of one element or one compound
a mixture consists of two or more different substances, not chemically joined together.
examples:
pure substance : Hydrogen gas - Diamond - Gold metal.
mixture : water and oil - mixtures of sand and water - trail mix
Explanation:
EVERY YEAR, NIKON <span>selects the most artful, scientifically enlightening and skillfully produced images from thousands of submissions for its </span>Small World<span> microscope photography contest. Tomorrow, another set of impressive winners will be announced for the contest’s 40th year.</span>
After 3 half life periods you would have 5 grams of krypton left because half of 40 is 20 half of 20 is 10 and half of 10 is 5
D. amu
amu stands for atomic mass unit
3 is the answer hope it helps
