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.
Mayonnaise is a heterogeneous mix. The correct answer is colloids.
To answer this question, you need to know <span>Graham's Law of Effusion/Diffusion formula. In this formula, the rate of diffusion/effusion would be influenced by the mass. As the molecule has bigger mass, the rate should be slower because it will be harder to pass the membrane. The calculation should be:</span>
<span>Rate 1 / Rate 2 = √[M2/M1]
</span>4.11/1= √[M2/2]
M2=33.78 g/mol
The theoretical yield is 204.4 g while the percent yield is 2.57%.
<h3>What is theoretical yield?</h3>
Theoretical yield is the amount of product obtained based on the stoichiometry of the reaction.
S8(s) + 8 Na2SO3(aq) + 40 H2O(l) --->8 Na2S2O3·5 H2O(s)
Number of moles of sulfur = 3.25 g /8(32) = 0.013 moles
Number of moles of sodium sulfite = 13.1 g/126 g/mol = 0.103 moles
Since 1 moles of sulfur reacts with 8 moles of sodium sulfite
0.013 moles reacts with 0.013 moles × 8 moles /1 mole = 0.104 moles
There is not enough sodium sulfite hence it is the limiting reactant.
1 mole of sodium sulfite yields 8 moles of product
0.103 moles of sodium sulfite yields 0.103 moles × 8 moles /1 mole = 0.824 moles
Mass of product = 0.824 moles × 248 g/mol = 204.4 g
percent yield = 5.26 g /204.4 g × 100/1
= 2.57%
Learn more about percent yield: brainly.com/question/2506978
