13. Classify the following as pure substances or as mixtures: -air
-gasoline
-grain alcohol
-water
-sugar
- gold
-mercury
-oxygen
-salt water

Determine the expected diffraction angle for the first-order reflection from the (310) set of planes for bcc chromium when monochromatic radiation of wavelength 0.0735 nm is used. the atomic radius for cr is 0.1249 nm.

Molten iron fills a mould, which has a volume of 200 cm cubed. calculate the volume when the iron cools and solidifies.

Four point charges each having charge q are located at the corners of a square having sides of length a. find symbolic expressions for the following. (a) the total electric potential at the center of the square due to the four charges (use any variable or symbol stated above along with the following as necessary: ke.) vtotal= (b) the work required to bring a fifth charge p from infinity to the center of the square (use any variable or symbol stated above along with the following as necessary: w=