Half-life refers to the time taken for half of the atoms in a radioactive substance to decay. Therefore in 1 half-life the 80 mg of substance will reduce to 40 mg. In another half-life it will reduce from 40 mg to 20 mg, then in a third half-life from 20 mg to 10 mg. Therefore the half-life is equal to the total time taken to decay from 80 mg to 10 mg divided by 3:
t(1/2) = 36 hours / 3 = 12 hours.
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Answer:
The mole is simply a very large number that is used by chemists as a unit of measurement.
Explanation:
The mole is simply a very large number,
6.022
×
10
23
, that has a special property. If I have
6.022
×
10
23
hydrogen atoms, I have a mass of 1 gram of hydrogen atoms . If I have
6.022
×
10
23
H
2
molecules, I have a mass of 2 gram of hydrogen molecules. If I have
6.022
×
10
23
C
atoms, I have (approximately!) 12 grams.
The mole is thus the link between the micro world of atoms and molecules, and the macro world of grams and litres, the which we can easily measure by mass or volume. The masses for a mole of each element are given on the periodic table as the atomic weight. So, if have 12 g of
C
, I know, fairly precisely, how many atoms of carbon I have. Given this quantity, I know how many molecules of
O
2
are required to react with the
C
, which I could measure by mass or by volume.
Answer: The 3rd and 6th bullet point is the quantitative data.
Explanation: Quantitative data is expressed by NUMBERS and Qualitative data is expressed by WORDS. The 3rd and 6th one is correct because they both use numbers to compare how much time hummingbirds spent feeding on nectar.
Answer:
powerhouse of the cell
Explanation:
Mitochondria produce ATP, a necessary sugar that runs the cell
Answer:
argon has an element structure of 2.8.8
