How many significant figures does 1261.631261.631261, point, 63 have?

What is the percent by mass of oxygen in fe2o3

Which theory was contradicted by experiments with the photoelectric effect? light spreads out after it passes through a small opening. as soon as light strikes metal, electrons will be ejected. visible light, regardless of color, will cause the ejection of electrons when striking metal. the kinetic energy of ejected electrons depends on the frequency of light that strikes the metal.

Chlorophyll a had the molecular formula c55h72mgn4o5 how many atoms are in this molecule