The table shows the amount of radioactive element remaining in a sample over a period of time. Radioactive Decay Rate

Amount of Radioactive Sample

(grams) Time(years)

56.0 - 0

47.1 - 400

39.6 - 800

33.3 - 1,200

28 - 1,600

Part 1: What is the half-life of the element? Explain how you determined this.

Part 2: How long would it take 312 g of the sample to decay to 9.75 grams? Show your work or explain your answer.

What is the correct equation for cellular respiration?

Which element has the lowest electronegativity? calcium(ca) gallium(ga) selenium(se) bromine(br)

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.