Whats the definition of collision?

Which other elements contain the same number of outer electrons as sodium

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.

4. a 20-kg child is tossed up into the air by her parent. the child is 2 meters off the ground traveling 5 m/s. circle one: ke / gpe / both show your work for finding the values of each type of energy the object has: