Ahydrogen atom emits a photon that has momentum 0.3059×10^(-27) kg·m/s. this photon is emitted because the electron in the atom falls from a higher energy level into the n = 4 level. what is the quantum number of the level from which the electron falls? use values of h = 6.626×10^-34 j·s, c = 2.998×10^8 m/s, and e = 1.602×10^(-19) c.

Laboratory experiments, observational field studies, and model-building are all examples of different forms of scientific investigations.  in what way do laboratory experiments primarily differ from other forms of scientific investigations?   a.  a laboratory experiment is the only accepted form of investigation within the scientific community.  b.  studies about how things behave in nature or studies involving very large objects are best answered through laboratory experiments.  c.  laboratory experiments involve the identification and control of variables.  d.  data can only be generated through laboratory experiments, not other forms of investigation.

In positive numbers less than 1, the zeros between the decimal point and non zero are significant

Acompound machine is also called a machine. a. force b. simple c. complex d. directional