Asteady circular light means drivers must stop at a marked stop line. a. green b. red c. yellow d. non of above

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.

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?

Glass has a hardness that is in the middle of the hardness scale. what is the hardness of glass?