a crane lifts a 450kg concrete to the top of a 50m building in 5s. assuming g=10m/s²,calculate a, the potential energy if the concrete​

Which statement about covalent bonds is true

Astudent is given an assignment to demonstrate diffraction. he takes a photograph of a straw in a glass of water. the straw appears bent at the water level. which best describes this example? a) this is a good example of diffraction. b) this is an example of dispersion and not diffraction. c) this is an example of refraction and not diffraction. d) this is an example of reflection and not diffraction.

True or false when elements combine to form a mixture, the resulting chemical properties may be very different from those of the elements that make it.