What does it mean to say that an electron's energy within an atom is quantized?

Enzymes affect the reactions in living cells by changing the

If 22.5 liters of oxygen reacted with excess of hydrogen, how many liters of water vapor could be produced?

[ou.03jthe pictures below show the wavelengths and intensities of electromagnetic radiations emitted by three stars, star 1, star 2, and star 3. intensity intensity- intensity- 1000 3500 6000 8500 11000 wavelength (a) star 1 1000 3500 6000 8500 11000 1000 3500 6000 8500 11000 wavelength (a) wavelength (a) star 2 star 3 which of these statements is correct about the color of the three stars? star 2 is white in color o star 2 is yellow in color star 1 and star 3 are yellow in color star 1 and star 3 are white in color