Answer:
28/44*100%=63.6%
Explanation:
the gram formula mass of N20 is 14*2+16=44.The mass of two nitrogen atom is 14*2=28,so the percentage is that 28/44*100%=63.6%.
Answer:
Chemistry has taught that ;
Unsaturated hydrocarbon molecules that contain one or more double bonds are called alkenes.
Alkynes are unsaturated hydrocarbons due to the fact that some of the carbons are connected to fewer than four neighbouring atoms.
Note : Alkenes contain at least one double bond, while alkynes contain at least one triple bond.
Explanation:
Answer:
Explanation:
A radioactive isotope is an isotope that undergoes nuclear decay, breaking apart into a smaller nucleus and emitting radiation during the process.
The half-life of an isotope is the amount of time it takes for a certain quantity of a radioactive isotope to halve.
For a radioactive isotope, the amount of substance left after a certain time t is:
(1)
where
is the mass of the substance at time t = 0
m(t) is the mass of the substance at time t
is the half-life of the isotope
In this problem, the isotope is uranium-235, which has a half-life of
We also know that the amount of uranium left in the rock sample is 6.25% of its original value, this means that
Substituting into (1) and solving for t, we can find how much time has passed:
Answer:
When you heat an atom, some of its electrons are "excited* to higher energy levels. When an electron drops from one level to a lower energy level, it emits a quantum of energy. ... The different mix of energy differences for each atom produces different colours. Each metal gives a characteristic flame emission spectrum.
Explanation:
