A chemical change occurs when . there is a change in the shape of a substance
there is a change in a state of a substance
there is a large increase in the size of the substance
there are one or more new substances with new properties formed

Embryos of different species look very similar, which shows that the organisms share a ancestor.

At 300 mm hg, a gas has a volume of 380 l, what is the volume at standard pressure

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.