Answer:
Explanation:
Between about 800 and 1200 AD, partly in response to the new currents of trade, Africans in the southern sahel developed a set of trading states with an elaborate organization.Well before 1500 AD, a number of states had come into existence, that had no connection at all with the trade across the Sahara.
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The time it takes for 1g of strontium-90 to decay to 250 mg is; 57.6 years
<h3>What is the half life of an element?</h3>
The formula for half life is;
A(t) = A₀ * (¹/₂)^(t/t_1/2)
Where;
A(t) is amount left after t years
A₀ the initial quantity of the substance that will undergo decay;
t_1/2 is the half-life of the decaying quantity.
We are given;
t_1/2 = 28.8 years
A₀ = 1 g
A(t) = 250 mg = 0.25 g
Thus;
0.25 = 1 * (¹/₂)^(t/28.8)
log 0.25 = (t/28.8) log (1/2)
-0.60206 = (t/28.8) * -0.3010
t = 2 * 28.8
t = 57.6 years
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Answer:
A. Tama
Explanation:
Hindi ko po sure kung tama
<span>The oil demand that is represented by large oil tankers is 2 million. The booming of business or oil tankers paved way to this happening. Many oil companies went down and maritime tankers closed during that period. A 2 million worth of oil is demanded to be represented by oil tankers that made the situation worst.</span>
