At which age do health officials recommend vaccinations begin?

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.

Can someone plz with questions 3 and 4 and if you can see question 5 then plz answer it . complete sentences. this is for masteries

What is a example of chemical weathering. a) erosion of land caused by receding glaciers. b)the layer of oxide formed on statues made of metal. c) deposition of silt along the bank of the mississippi river. d)weathering of rocks in a desert due to the rapid rise and fall of temperatures