A common issue in nuclear medicine is the short half-life of materials used for tests like PET or CT scans. The materials must be manufactured nearby so that they can be transported to a hospital quickly enough to be used for a patient when needed. It can be a tremendous advantage for a hospital to be near a laboratory capable of manufacturing rare isotopes. A good example of this is the F-18 isotope used for PET scans. It has a half-life of about 110 minutes. If a 50.0 mg sample of F-18 leaves the laboratory at 8:00 am, how many milligrams of F-18 remains in the sample when it arrives at the hospital at 1:30 pm?

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72

a electronegativity decreases beacuse the size of nucleus is bigger.

the dissociation of nickel hydroxide is follows:

the concentration of hydroxide ion is

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

thus, concentration of ni is 0.23 * 10^-^4 mol /l