Is this showing a lunar or solar eclipse? Explain what is happening from the viewpoint of Earth.

How many grams of aluminum will there be in 98g of al2o3?

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

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.