P l e a s e h e l p m e
write an Explanation for why Sun spots occur

What must occur for air masses to form fronts

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.

The polymer used for the nonstick surface of cooking utensils is 24.0%c and 76%f by mass. what is the empirical formula of this polymer?