The amount of substance present in a certain sample can be calculated through the equation,
A(t) = A(o)(0.5)^(t/h)
where At is the amount now, Ao is the original amount, t is the number of years and h is the half-life.
For a substance to at most 50% of the original amount, we get the half-life value.
At/Ao = 0.5 = 0.5^(4.5/h)
h = 4.5 billion.
All values below 4.5 billion as half-life are accepted. From the given list, the substances that would be less than 50% now are:
<em>Uranium - 238 ; Uranium -235 and ; Postassium-40</em>
The size and the temperature affects the luminosity of a star
1 mole Zn ---------- 6.02 x 10²³ atoms
0.750 moles Zn ----- ?
atoms = 0.750 * ( 6.02 x 10²³ / 1 )
= 4.515 x 10²³ atoms
hope this helps!
The balanced equation is C6H14(g)
+ 19/2O2(g) → 6CO2(g) + 7H2O(g). If you are given 7.9 moles C6H14, multiply it
by a ratio of 19/2/1 to get the moles of oxygen. Then, you will get 75.05 moles
of O2.
Answer:
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