Fluorine-21 has a half -life of approximately 5 seconds. how much of a 200 gram sample would remain after 1 minute

0.0488 g

We are given

The radioisotope Fluorine-21

Half-life is 5 seconds

Initial mass of Fluorine-21 is 200 g

Time = 1 min or 60 seconds

Required to determine the New mass after decay

New mass = Original mass × (1/2)^n , where n is the number of half lives.

In this case, n = 60 s ÷ 5 s

                       = 12

New mass = 200 g × (1/2)^12

                 = 200 g × 1/4096

                = 0.0488 g

Therefore, the mass of Fluorine-21 remaining after 1 minute is 0.0488 g

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

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