With various extractions the amount of material left in the trash will be lower, ergo the extraction will be more perfect. Various extractions with fewer amounts of solvent are more efficient than a single extraction with a huge amount of solvent.
<u>Explanation:</u>
Surely multiple extractions are better than the single large extraction. Because extraction is about maximizing outside field communication between the two solvents, and you easily get more surface area contact with fewer amounts.
You can merge two smaller portions quicker and more completely than with large portions.
Half-life of a radioactive substance is the time required to reduce the amount of substance to half of its initial amount.
In present case, half-life is material is given as 1000 years and initial amount of material is given as 400 kg
Answer 1) Since, half-life of radio-active substance is 1000 years, therefore after 1st half life, amount of the material will be left to half the initial amount. Hence, amount of substance left after 1000 years = 400/2 = 200 kg.
Answer 2) For 2000 years, radioactive material has crossed 2 times the half life. Therefore , amount of the material will be left to 1/4 the initial amount. Hence, amount of substance left after 2000 years = 400/4 = 100 kg.
Answer 3) For 4000 years, radioactive material has crossed 4 times the half life. Therefore , amount of the material will be left to 1/16 the initial amount. Hence, amount of substance left after 4000 years = 400/16 = 25 kg.
Radiant energy or electrical energy
