How many moles of copper are needed to react with sulfur to produce 0.25 moles of copper(I) sulfide according to 2Cu+S=Cu2S

Stage in which a star’s outer layers have started to cool and grow outward?

The chemical bond connecting one nucleotide with the next one along the nucleic acid chain is called a

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.