Answer:
B
Explanation:
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Answer:
B. II.
Explanation:
The idea of recrystallization works when the solubility of the target substance decreases as the temperature of the solution decreases.
The method of recrystallization involves dissolving the solute in a suitable hot solvent and then allow the solution to cool gradually. The pure solute dissolves in the hot solvent and then separates out of the solution as it is cooled to room temperature.
Hence recrystallization is preferred over solvent extraction when the desired compound is poorly soluble in the solvent pair at low temperatures and greatly soluble in the solvent pair at high temperatures.
0.84 milligrams of a 2. 000 mg sample remain after 6. 55 years, according to radioactive decay.
Given data,

amount of sample = 2.000mg initially = 0.002grams
According to radioactive decay,

(
)λ =
=
= 0.133
According to radioactive decay,

- λt
= ln0.002 - (0.133×6.55)
= -6.21 - 0.87 = -7.08 = 0.00084g = 0.84mg
Therefore, 0.84 milligrams of a 2. 000 mg sample remain after 6. 55 years.
Learn more about radioactive decay here:
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