Answer: It will take 29 years for a 10.0-gram sample of strontium-90 to decay to 5.00 grams
Explanation:
Radioactive decay process is a type of process in which a less stable nuclei decomposes to a stable nuclei by releasing some radiations or particles like alpha, beta particles or gamma-radiations. The radioactive decay follows first order kinetics.
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
Half life is represented by 
= rate constant
Given : Strontium-90 decreases in mass by one-half every 29 years , that is half life of Strontium-90 is 29 years.
As half life is independent of initial concentration, it will take 29 years for a 10.0-gram sample of strontium-90 to decay to 5.00 grams as the amount gets half.
A change of one unit on the pH scale represents a change in the concentration of hydrogen ions by a factor of 10, a change in two units represents a change in the concentration of hydrogen ions by a factor of 100. Thus, small changes in pH represent large changes in the concentrations of hydrogen ions.
In this problem, you’re given a mass (m) and a force (F) applied to an object and you’re asked to calculate the acceleration (a). If we plug this into the provided equation:
F = ma
(7.3 N) = (3.2 kg)a
a = 2.3 m/s/s
The acceleration of the object is 2.3 m/s/s.
Hope this helps!
<u>Answer:</u>
<em>The system is the Answer
</em>
<em></em>
<u>Explanation:</u>
System is the region which is taken into consideration.
While we perform a chemical reaction the system is the substance taken in the container.
So, A thermodynamic system is the amount of matter or the region in universe which is under the study.
The region outside the beaker are called as surroundings.
The beaker (the surface which separates the system from its surroundings) is said to be the boundary
System + surroundings = universe
We are told that there are 1.55 x 10²³ molecules of Cl₂ and we need to calculate the mass of these molecules. We need to do several conversions. The easiest will be to convert the amount of molecules to the number of moles present. To do this, we need to use Avogadro's number which is 6.022 x 10²³ molecules/mole.
1.55 x 10²³ molecules / 6.022 x 10²³ molecules/mole = 0.257 moles Cl₂
Now that we have the moles of Cl₂ present, we can convert this value to a mass of Cl₂ by using the molecular mass of Cl₂. The molecular mass is 70.906 g/mol.
0.257 moles Cl₂ x 70.906 g/mol = 18.3 g Cl₂
Therefore, 1.55 x 10²³ molecules of Cl₂ will have a mass of 18.3 g.
