It would take 147 hours for 320 g of the sample to decay to 2.5 grams from the information provided.
Radioactivity refers to the decay of a nucleus leading to the spontaneous emission of radiation. The half life of a radioactive nucleus refers to the time required for the nucleus to decay to half of its initial amount.
Looking at the table, we can see that the initial mass of radioactive material present is 186 grams, within 21 hours, the radioactive substance decayed to half of its initial mass (93 g). Hence, the half life is 21 hours.
Using the formula;
k = 0.693/t1/2
k = 0.693/21 hours = 0.033 hr-1
Using;
N=Noe^-kt
N = mass of radioactive sample at time t
No = mass of radioactive sample initially present
k = decay constant
t = time taken
Substituting values;
2.5/320= e^- 0.033 t
0.0078 = e^- 0.033 t
ln (0.0078) = 0.033 t
t = ln (0.0078)/-0.033
t = 147 hours
Learn more: brainly.com/question/6111443
Answer:
9.55 grams of SiO2
Explanation:
If the mass you mean by grams:
0.159 mole x 60.08 g (Periodic table by adding both elements)
Cancel moles with moles (Original moles with the 1 mol at the bottom of the grams) and gives you:
9.55 grams of SiO2
It’s ionic bond based on electrons gain/loss.
Answer:
The Net reaction is
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Explanation:
From the Question we are told that the buffers are
and 
When NaOH is added the Net ionic reaction would be
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<u>Answer:</u>
2.0158 grams
<u>Explantion:</u>
We are to find the mass of the hydrogen atoms in 1 mole of water.
We know that the formula of water is: 
We can see, from the above mentioned formula, that water has 2 hydrpgen atoms.
From the periodic table, we get to know that Hydrogen has an atomic mass of 1.00794 grams.
As there are 2 atoms of hydrogen in water so 
grams is the answer
