Which among the following represents a set of isotopes? Atomic nuclei containing: a) 20 protons and 20 neutrons

b) 21 protons and 19 neutrons

c) 22 neutrons and 18 protons

d) 20 protons and 22 neutrons

e) 21 protons and 20 neutrons

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.

Rank substituents in order of their priority when assigning the e or z label to an alkene. i, ch2i , h, ch2ch2cl, f

A250 g sample of water with an initial temperatureof 98.8 closes 6500 joules of heat. what is the finaltemperature of the water?