Deuterium is an of hydrogen because it has one proton and one neutron in its whereas hydrogen only has one proton.
a. element, nucleus
b. element, valence shell
c. isotope, nucleus
d. isotope, valence shell

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.

How many moles are in 43.9 l of oxygen

How many grams of sodium chloride are in 250ml of a 2.5m naci solution