Explain how you could find out whether of not an unknown liquid is water

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?

Ais useful when you need a simple machine to you separate two things. a. lever b. screw c. pulley d. wedge

What are igneous intrusions and extrusions