A scientist is studying a radioactive element that has a half-life of 63 years. Choose the correct answers from the drop-down menus to complete each statement about the element. It will take
years for half of the sample to decay.

In 189 years,
of the sample will be left.

Scientists can figure out how old a sample is by multiplying the
by the length of the half-life.

**40** points asapessay questions (10 points possible) clear image of next, create your own scenario. it can be one of your own real experiences or one you make up. use imagery in your writing to give your instructor a the setting and an action taking pace in your writing explain the structure and functions of the skin at work in your scenario. !

Which statements describe polyatomic ions? check all that apply. polyatomic ions have many charges. polyatomic ions have one overall charge. polyatomic ions repel other ions to form ionic bonds. polyatomic ions attract other ions to form ionic bonds. polyatomic ions are made up of only one type of atom. polyatomic ions are made up of two or more types of atoms.

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.