In a machine, parts come into contact with surfaces and decreases the amount of energy that the machine uses to produce work. How does the law of conservation of energy explain this?
a: the parts dont always line up resulting in energy loss
b: the parts rub against surfaces generating friction and resulting in heat
c: only machines with multiple parts have this problem
d: 100% of energy put into the machine results in work

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.