the images below show two commonly observed changes.

which statement correctly describes one of the changes?
a) picture i shows a chemical change, because a new substance is formed.
b) picture ii shows a chemical change, because a new substance is formed.
c) picture i shows a chemical change, because the same substance changes form.
d) picture ii shows a chemical change, because the same substance changes form.

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.