a 500 kilogram sample of substance decays to 125 kilograms over a period of 21.53 years. what is the half life of the sample substance

Half life = 10.765 year

Explanation:

Given data:

Mass of sample = 500 Kg

Mass left after 21.53 years = 125 kg

Half life of substance = ?

Solution:

At tome zero = 500 kg

At 1st half life = 500 kg/2 = 250 kg

At 2nd half life = 250 kg/2 = 125 g

Half life:

Half life = time elapsed / number of half life

Half life = 21.53 year/2

Half life = 10.765 year

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!

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