Which of these is not true about the proton?
a. when a neutral hydrogen atom loses an electron, the proton remains.
b. a proton is about 2000 times heavier than an electron.
c. electrons surrounding atoms get pulled into the nucleus by protons.
d. protons exist within the nuclei of atoms.

In 2002, the rare earth elements mine in mountain pass, california was closed because

Acompound has a molar mass of 92.02 grams/mole, and its percent composition is 30.4% nitrogen (n) and 69.6% oxygen (o). what is its molecular formula? a. n2o4 b. no2 c. n2o d. n4o2

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.