I do believe all of these but core elements can be determined by spectroscopy which includes the use of electromagnetic radiation. Both the surface and core temperature can be measured using light. Surface elements can be found because the absorption lines of different elements in the spectra of the star, but I haven't heard anything about using spectral analysis for core elements.
Answer:
Explanation:
velocity=frequency*wavelength
velocity = 2.99*10^8 m/s
frequency = ?
wavelength = 3.012*10^-12
2.99*10^8m/s = (f)(3.012*10^-12)
f=9.58*10^19 Hertz
Greetings!
"<span>How many significant figures does 0.00340 have?"...
A significant figure is:
-A non zero number
-A zero in between non zero numbers
-Trailing zeros to the right of the decimal point
Therefore, this number has three significant figures:
3,4,0
Hope this helps.
-Benjamin</span>
I do not agree with the statement.
The "substance" can be a compound. It's "pure"
as long as there's nothing else in it but its name.
'Pure' water is 100% H₂O with nothing else in it.
'Pure' table salt is 100% NaCl with nothing else in it.
'Pure' carbon dioxide is 100% CO₂ with nothing else in it.
These example substances are all compounds, not elements.