Question 3 Every few hundred thousand years, the magnetic poles of Earth reverse. Rocks that contain iron provide a record of both normal and reversed magnetic
poles. The diagram below shows the pattern of normal and reversed magnetic poles as recorded in the rocks on either side of the Mid-Atlantic Ridge
How does this show evidence of seafloor spreading?

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.