Answer:
I think it the carbon 14 which is a half life of 5730 because in 4.5billion years ago I don't think any human being existed on earth I'm not sure I hope that I helped you and good luck .
Answer:
The concentration is 
Explanation:
From the question we are told that
The absorbance is 
The length is 
Generally absorbance is mathematically represented as

where
is the molar absorptivity of FeSCN2 with a value 
and
is the equilibrium concentration of FeSCN2
So

substituting values


Ar (argon) has 18 electrons
Cl- would give you 18 electrons
F- would give you 10 electrons
Li+ would give you 2 electrons
Na+ would give you 10 electrons
Cl- would be the correct answer
Answer : The number of moles in 369 grams of calcium hydroxide is, 4.98 moles
Explanation : Given,
Mass of calcium hydroxide = 369 g
Molar mass of calcium hydroxide = 74.093 g/mole
Formula used :

Now put all the given values in this formula, we get the moles of calcium hydroxide.

Therefore, the number of moles in 369 grams of calcium hydroxide is, 4.98 moles
Answer:
A
Explanation:
Hot air is less dense therefore it rises. Cold air is more closely packed therefore it is more dense. Less dense things rise while more dense things sink.