For first -order radioactive decay- $A_{t}=A_{0}(\frac{1}{2})^{\frac{t}{t_{\frac{1}{2}}}}$
$A_{t}$ represents activity of radioactive nuclide after t time, $A_{0}$ represents initial activity of radioactive nuclide and $t_{\frac{1}{2}}$ represents half-life
Here, $A_{t}=19Bq$ , $A_{0}=20Bq$ and $t_{\frac{1}{2}}=5.73\times 10^{3}years$

Plug-in all the given values in the above equation-

$19=20\times (\frac{1}{2})^{\frac{t}{5.73\times 10^{3}}}$

or, $t=4.2\times 10^{2}$

So, age of the atifact is $4.2\times 10^{2}$ years

6 0

2 years ago

Roundup, an herbicide manufactured by Monsanto, has the formula C₃H₈NO₅P. How many moles of molecules are there in a 304.3-g sam

jekas [21]

<span>The molar mass is 169.09

304.3g/169.09g = 1.799mol which rounds to 1.800 mol</span>

7 0

2 years ago

If atmospheric pressure suddenly changes from 1.00 atm to 0.892 atm at 298 k, how much oxygen will be released from 4.40 l of wa

garri49 [273]

Henry's law constant for oxygen is 0,0013 mol/L·<span>atm. Air has 21,0% oxygen.
concentration of oxygen at 1 atm: 0,0013 mol/L</span>·atm · 0,21 · 1 atm = 0,000273 mol/l.
concentration of oxygen at 1 atm: 0,0013 mol/L·atm · 0,21 · 0,892 atm = 0,000243 mol/l.
difference in concentration: 0,000273 - 0,000243 = 0,00003 mol/L.
n(oxygen) = 0,00003 mol/L · 4,40 L = 0,000132 mol.

4 0

3 years ago

A person who has a mass of 60kg run up a flight of stairs 12m high in 20 seconds What is the weight of the person​

A person who has a mass of 60kg run up a flight of stairs 12m high in 20 seconds What is the weight of the person