Equation for Half life :
A = a(0.5)^(t/h)
A is current amount, "a" is initial amount, h is halflife, t is time
5 = 40(0.5)^(t/1.3x10^9)
5/40 = (0.5)^(t/1.3x10^9)
take the log of both sides , power rule
Log(5/40) = (t/1.3x10^9) * Log(0.5)
(1.3x10^9) * Log(5/40) / Log(0.5) = t
3.9x10^9 years = t
And if you think about what a half life is, the time it take for the amount to reduce to half.
40/2 = 20
20/2 = 10
10/2 = 5
It went through 3 half-lifes
3 * 1.3x10^9 = 3.9x10^9 years
Answer:
active transport requires energy and passive transport does not require energy
Explanation:
Answer:
Final temperature of water is 
Explanation:
1 mol of LiBr releases 48.83 kJ of heat upon dissolution in water.
So, 2 moles of LiBr release
or 97.66 kJ of heat upon dissolution in water.
This amount of heat is consumed by 1000.0 g of water. Hence temperature of water will increase.
Let's say final temperature of water is
.
So, change in temperature (
) of water is
or (t-25) K
Heat capacity (C) of water is 
Hence, 
where m is mass
So, 
or, 
Hence final temperature of water is 