Why is the average atomic mass used when calculating grams of a substance?
A. The number of isotopes in the sample is constantly changing.
B. The elements in the substance are mixtures of their isotopes.
C. The average atomic mass is known to more significant figures.
D. The exact weights of the isotopes are not known.

The table describes how some substances were formed substance 19 description formed by boiling pure water formed by combining three hydrogen atoms to every nitrogen atom formed by adding 5 g of sugar to 1 l of water formed by compressing carbon under high pressure based on the given descriptions, which substance is most likely a mixture?

2pos suppose an object in free fall is dropped from a building. its starting velocity is 0 m/s. ignoring the effects of air resistance, what is the speed (in m/s) of the object after falling 3 seconds? give your answer as a positive decimal without units. answer here

Which characteristics can be used to differentiate star systems? check all that apply.