10. Avogadro's number can be used to find the number of atoms in an element.- T

12. A photon is a quantum of light energy.- T

17. The atomic mass unit is determined by Oxygen-16.- F

18. The number of particles in a mole is a constant.- T

19. The number of protons is always equal to its number of neutrons.- F

20. Wavelength is the distance between corresponding points on adjacent waves.- T

21. Frequency is the number of waves that pass a given point, usually in one second.- T

Thanks
-MC

all correct.

Your answers are correct for questions 10, 12, 18, 20, and 21. Great job!

For question 17, the statement is incorrect. The atomic mass unit (amu) is actually determined by the mass of the carbon-12 isotope, not oxygen-16. One atomic mass unit is defined as 1/12th the mass of a carbon-12 atom.

For question 19, the statement is also incorrect. The number of protons in an atom, which determines its atomic number, is not always equal to the number of neutrons. The number of neutrons can vary and different isotopes of the same element can have different numbers of neutrons.

If you would like to verify or find more information about any of these statements, you can conduct a quick search online using a reputable scientific source or refer to a chemistry textbook.