It will take 28 days to let the radioactivity fall below 25%.
<h3>What is Half Life ?</h3>
Half life can be described as the time required by the radioactive compound to reduce to half of the original value of concentration.
It is given that
Radioactive phosphorus-32 decays with a half-life of 14.0 days
25% of the initial measure at what time =?
For 50% decay the time needed is 14 days
for decay of the next 50% of the amount left the time taken will be another 14 days
2nd half life = 25% decay of the substance = 28 days
Therefore it will take 28 days to let the radioactivity fall below 25%.
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As we know,
1 mole of any substance contains 6.022 × 10²³ particles. And 1 mole of NO₂ (equal to 46 g) contains 6.022 × 10²³ Molecules. Hence,
6.022 × 10²³ Molecules of NO₂ = 46 g
So,
2.4 × 10²³ Molecules of NO₂ = X g
Solving for X,
X = (2.4 × 10²³ Molecules × 46 g) ÷ 6.022 × 10²³ Molecules
X = 18.33 g
Oxygen is the second component of the atmosphere in terms of volume.
Answer:
a. atoms are made up of mostly empty space.(this is because most of the atoms were able to pass through the gold foil undeflected)
Explanation: