The number of years required for 1/4 cobalt-60 to remain after decay is calculated as follows
after one half life 1/2 of the original mass isotope remains
after another half life 1/4 mass of original mass remains
therefore if one half life is 5.3 years then the years required
= 2 x 5.3years = 10.6 years
Answer:
Approximately 
.
Explanation:
Note that both figures in the question come with four significant figures. Therefore, the answer should also be rounded to four significant figures. Intermediate results should have more significant figures than that.
<h3>Formula mass of strontium hydroxide</h3>
Look up the relative atomic mass of 
, 
, and 
on a modern periodic table. Keep at least four significant figures in each of these atomic mass data.
Calculate the formula mass of 
:
.
<h3>Number of moles of strontium hydroxide in the solution</h3>
means that each mole of formula units have a mass of 
.
The question states that there are 
of in this solution.
How many moles of formula units would that be?
.
<h3>Molarity of this strontium hydroxide solution</h3>
There are 
of formula units in this 
solution. Convert the unit of volume to liter:
.
The molarity of a solution measures its molar concentration. For this solution:
.
(Rounded to four significant figures.)
Answer:
0.0277 M.
Explanation:
The integral rate law of a first order reaction:
<em>Kt = ln ([A₀]/[A]),</em>
where, k is the rate constant of the reaction <em>(k = 3.36 × 10⁻⁵ s⁻¹)</em>,
t is the time of the reaction <em>(t = 235.0 min = 14100 s)</em>,
[A₀] is the initial concentration of cyclopropane <em>([A₀] = 0.0445 M)</em>
<em>∵ Kt = ln ([A₀]/[A]),</em>
∴ (3.36 × 10⁻⁵ s⁻¹)(14100 s) = ln (0.0445 M)/[A]
Taking the exponential of both sides:
1.6 = (0.0445 M)/[A]
<em>∴ [A] = (0.0445 M)/1.6 = 0.0277 M.</em>
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Answer:There is no relationship between the viscosity and density of a fluid. While viscosity is the thickness or thinness of a fluid, density refers to the space between its particles. However, both properties are affected by temperature. When a fluid is heated, its particles move far apart, and it also becomes less viscous.
Answer:
A. Engineers come up with scientific questions when they are developing their design, and scientists do research to answer them.
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