what is the sterochemistry relationship between (2S,3R)-2,3-dibromopheptnoic acid and (2R,2S)-2,3-dibromoheptanoic acid

Different isotopes indicate that an element will have different numbers of

Tin has ten stable isotopes. the heaviest, 124sn, makes up 5.80% of naturally occuring tin atoms. how many atoms of 124sn are present in 82.0 g of naturally occurring tin? what is the total mass of the 124sn atoms in this sample?

Measurements that have similar values are: a. usually accurate b. sometimes accurate c. always accurate d. never accurate