The half-life of sodium-24 is 15 hours, how much of the 16 g remains after
60 hours?

After 60 hours 1 g is left.

Explanation:

Given data:

Half life of sodium = 15 hours

Total amount = 16 g

Amount remain after 60 hours = ?

Solution:

First of all we will calculate the number of half lives:

Number of half lives = Time elapsed / half life

Number of half lives = 60 hours / 15 hours

Number of half lives = 4

Amount left:

At time zero = 16 g

At first half life = 16 g/2= 8 g

At 2nd half life = 8 g/2 = 4 g

At 3rd half life = 4 g/2 = 2 g

At 4th half life = 2 g/2 = 1 g

After 60 hours 1 g is left.

the answer would be a

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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~ trueboss72