Answer:
E = hf
E = hc/lamda
where E-energy,
h-planck's constant (6.62 x 10^-34 Js)
f- frequency ( f = c/lamda)
c-velocity of light ( 3 x 10^8 m/s)
lamda- wavelength
you can this formula to solve all the 4 questions.
Answer:
i am pretty sure it is compound
The elements in each group have the same number of electrons in the outer orbital. Or also called valence electrons. Khan academy has a great video online explaining why this happens. (It only happens for main group elements). Here is a link (sorry you can’t click it in Brainly) https://www.khanacademy.org/science/chemistry/periodic-table/copy-of-periodic-table-of-elements/v/periodic-table-valence-electrons. Feel free to message me for a better explanation, I would explain now but I’m not sure how much you know about this. If you know how to write an electron configuration you can see how all the electron configurations for the same group (not the transitional metals only the main groups) have the same number of valence electrons. I hope that helped, sorry I was vague about the explanation :)
Answer:
0.01395mol Cr2O3
Explanation:
the molar mass of Cr2O3 is 151.9904 g/mol
2.12g Cr2O3 x 1 mol/151.9904g = 0.01395mol Cr2O3
